Electrosurgical system

ABSTRACT

An electrosurgical generator arranged to supply radio frequency (RF) energy to fuse tissue is provided. The generator is arranged to supply RF energy through a removably coupled electrosurgical instrument to fuse tissue grasped by the instrument. The generator monitors a phase angle of the supplied RF energy and adjusts or terminates the supplied RF energy based on the monitored phase angle in comparison to predetermined thresholds and conditions to optimally fuse the tissue. The electrosurgical instrument conducts radio frequency energy to fuse tissue captured between the jaws and a blade to mechanically cut tissue between the jaws. A conductive post positioned on the jaw adjacent to the blade.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is application is a continuation of U.S. Pat. Application No.16/209,759, filed Dec. 4, 2018, which is a continuation of U.S. Pat.Application No. 14/848,116, filed Sep. 8, 2015, now issued U.S. Pat. No.10,149,713, which is a continuation of International Application No.PCT/US2015/031452, filed May 18, 2015, which claims the benefit of U.S.Provisional Application No. 61/994,192, filed on May 16, 2014; USProvisional Application No. 61/994,185, filed on May 16, 2014; U.S.Provisional Application No. 61/994,415, filed on May 16, 2014; and U.S.Provisional Application No. 61/994,215, filed May 16, 2014, the entiredisclosures of which are incorporated by reference as if set forth infull herein.

BACKGROUND

The present application relates generally to electrosurgical systems andmethods and more particularly relates to electrosurgical generators andadvanced bipolar electrosurgical devices or instruments.

Electrosurgical devices or instruments have become available that useelectrical energy to perform certain surgical tasks. Typically,electrosurgical instruments are hand tools such as graspers, scissors,tweezers, blades, needles, and other hand tools that include one or moreelectrodes that are configured to be supplied with electrical energyfrom an electrosurgical generator including a power supply. Theelectrical energy can be used to coagulate, fuse, or cut tissue to whichit is applied.

Electrosurgical instruments typically fall within two classifications:monopolar and bipolar. In monopolar instruments, electrical energy issupplied to one or more electrodes on the instrument with high currentdensity while a separate return electrode is electrically coupled to apatient and is often designed to minimize current density. Monopolarelectrosurgical instruments can be useful in certain procedures, but caninclude a risk of certain types of patient injuries such as electricalburns often at least partially attributable to functioning of the returnelectrode. In bipolar electrosurgical instruments, one or moreelectrodes is electrically coupled to a source of electrical energy of afirst polarity and one or more other electrodes is electrically coupledto a source of electrical energy of a second polarity opposite the firstpolarity. Thus, bipolar electrosurgical instruments, which operatewithout separate return electrodes, can deliver electrical signals to afocused tissue area with reduced risks.

Even with the relatively focused surgical effects of bipolarelectrosurgical instruments, however, surgical outcomes are often highlydependent on surgeon skill. For example, thermal tissue damage andnecrosis can occur in instances where electrical energy is delivered fora relatively long duration or where a relatively high-powered electricalsignal is delivered even for a short duration. The rate at which atissue will achieve the desired coagulation or cutting effect upon theapplication of electrical energy varies based on the tissue type and canalso vary based on pressure applied to the tissue by an electrosurgicalinstrument. However, even for a highly experienced surgeon, it can bedifficult for a surgeon to assess how quickly a mass of combined tissuetypes grasped in an electrosurgical instrument will be fused a desirableamount.

Attempts have been made to reduce the risk of tissue damage duringelectrosurgical procedures. For example, previous electrosurgicalsystems have included generators that monitor an ohmic resistance ortissue temperature during the electrosurgical procedure, and terminatedelectrical energy once a predetermined point was reached. However, thesesystems have had shortcomings in that they can provide inconsistentresults at determining tissue coagulation, fusion, or cutting endpointsfor varied tissue types or combined tissue masses. These systems canalso fail to provide consistent electrosurgical results among use ofdifferent instruments having different instrument and electrodegeometries. Typically, even where the change is a relatively minorupgrade to instrument geometry during a product’s lifespan, theelectrosurgical generator must be recalibrated for each instrument typeto be used, a costly, time consuming procedure which can undesirablyremove an electrosurgical generator from service.

SUMMARY

In certain embodiments, an electrosurgical system for performingelectrosurgical procedures on body tissue of a patient comprises anelectrosurgical generator and a bipolar electrosurgical device orinstrument. The generator controls the delivery of electrosurgicalenergy to fuse tissue in contact with the bipolar electrosurgicaldevice. The generator in various embodiments identifies a phase zerocrossing, adjusts the RF energy output or voltage and measures andmonitors a phase angle and/or a change of phase angle rate relative to apredetermined threshold with the predetermined threshold identified atthe identified phase zero crossing.

In accordance with various embodiments, an electrosurgical fusion devicecomprises first jaw coupled to a second jaw with the first jaw having afirst electrode and the second jaw having a second electrode facing thefirst electrode. The first and second electrodes are arranged to conductradio frequency (RF) energy between the first and second electrodes andthe first and second electrodes are made of the same conductivematerial. The electrosurgical fusion device also includes an elongateshaft having a proximal end and a distal end and a longitudinal axisextending from the proximal end to the distal end, the first and secondjaws being pivotably coupled to the distal end of the elongate shaft.The elongate shaft in one embodiment has an outer diameter of less than5 mm to fit through a 5 mm cannula.

In accordance with various embodiments, the electrosurgical fusiondevice comprises a conductive post incorporated into the second jaw andextending from the second jaw towards the first jaw. The conductive postis stationary and is made of the same conductive material as the firstand second electrodes. In various embodiments, the conductive postincludes a plurality of conductive posts having varying heights.

In accordance with various embodiments, the electrosurgical fusiondevice comprises a first jaw having a conductive pad with a second jawcoupled to the first jaw. The second jaw having an inner surface facingthe conductive pad with the first and second jaws arranged to capturetissue between the conductive pad and the inner surface of the secondjaw. The conductive pad and the second jaw are arranged to connect to anelectrosurgical energy source and arranged to conduct RF energy throughtissue held between the jaws. The electrosurgical fusion device alsocomprises a blade movable along a longitudinal axis from a proximalposition to a distal position and back to the proximal position with theblade disposed within an outer periphery of the second jaw.

In accordance with various embodiments, the electrosurgical fusiondevice comprises a conductive post disposed on the second jaw andadjacent to the blade. The conductive post is arranged to not connect tothe electrosurgical energy source and is arranged to conduct RF energybetween the conductive pad or the second jaw through the tissue heldbetween the jaws.

Many of the attendant features of the present inventions will be morereadily appreciated as the same becomes better understood by referenceto the foregoing and following description and considered in connectionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present inventions may be better understood taken in connection withthe accompanying drawings in which the reference numerals designate likeparts throughout the figures thereof.

FIG. 1 is a perspective view of an electrosurgical system in accordancewith various embodiments of the present invention.

FIG. 2 is a perspective view of an electrosurgical generator inaccordance with various embodiments of the present invention.

FIG. 3 is a flow chart illustrating operations of an electrosurgicalsystem in accordance with various embodiments of the present invention.

FIG. 4-1 to 4-2 are schematic block diagrams of an embodiment ofelectrosurgical system.

FIGS. 5 to 6 are schematic block diagrams of portions of anelectrosurgical system in accordance with various embodiments of thepresent invention.

FIGS. 6-1 is a schematic block diagram of portions of an electrosurgicalsystem in accordance with various embodiments of the present invention.

FIGS. 6-2 is a signal diagram illustrating operations of anelectrosurgical system in accordance with various embodiments of thepresent invention.

FIGS. 6-3 is a schematic block diagram of portions of an electrosurgicalsystem in accordance with various embodiments of the present invention.

FIG. 6-4 to 6-12 are signal diagrams illustrating operations of anelectrosurgical system in accordance with various embodiments of thepresent invention.

FIGS. 7 to 9 are schematic block diagrams of portions of anelectrosurgical system in accordance with various embodiments of thepresent invention.

FIG. 10 is a flow chart illustrating operations of an electrosurgicalsystem in accordance with various embodiments of the present invention.

FIGS. 11A-11B are flow charts illustrating operations of anelectrosurgical system in accordance with various embodiments of thepresent invention.

FIGS. 12-20 are graphical representations of exemplary data or resultsprovided by an electrosurgical system in accordance with variousembodiments of the present invention.

FIG. 21 is a perspective view of an electrosurgical fusion device inaccordance with various embodiments of the present invention.

FIG. 22 is a perspective view of a portion of an electrosurgical fusiondevice in accordance with various embodiments of the present invention.

FIG. 23 is a perspective view of a distal end of the electrosurgicaldevice in accordance with various embodiments of the present invention.

FIG. 24 is a perspective view of a distal end of an electrosurgicaldevice in accordance with various embodiments of the present invention.

FIG. 25 is a side cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 26 is a side view of a distal end of an electrosurgical device inaccordance with various embodiments of the present invention.

FIG. 27 is a side cross-sectional view of an electrosurgical device inaccordance with various embodiments of the present invention.

FIG. 28 is a side view of a distal end of an electrosurgical device inaccordance with various embodiments of the present invention.

FIG. 29 is a side cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 30 is a side cross-sectional view of an electrosurgical device inaccordance with various embodiments of the present invention.

FIG. 31 is a side cross-sectional view of a portion of an actuator of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 32 is a side cross-sectional view of an electrosurgical device inaccordance with various embodiments of the present invention.

FIG. 33 is a side cross-sectional view of a portion of an actuator of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 34 is a side cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 35 is a front cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 36 is a perspective view of a post in accordance with variousembodiments of the present invention.

FIG. 37 is a side view of a post in accordance with various embodimentsof the present invention.

FIG. 38 is a front cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 39 is a front cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

FIG. 40 is a front cross-sectional view of a distal end of anelectrosurgical device in accordance with various embodiments of thepresent invention.

DETAILED DESCRIPTION

In accordance with various embodiments, an electrosurgical system isprovided that includes an electrosurgical generator and anelectrosurgical instrument that are configured to optimally fuse tissue.The electrosurgical instrument in accordance with various embodiments isprovided to be used in laparoscopic surgery with the ability to move,grasp and compress tissue and to deliver RF energy to fuse the tissue.In accordance with various embodiments, the electrosurgical instrumentis a bipolar electrosurgical instrument insertable through a 5 mm trocarand cuts tissue through actuation of a mechanical cutting blade. The RFenergy is supplied by the electrosurgical generator configured toprovide the appropriate RF energy to fuse the tissue. The generator inaccordance with various embodiments determines the appropriate RF energyand the appropriate manner to deliver the RF energy for the particularconnected electrosurgical instrument, the particular tissue in contactwith the instrument and/or a particular surgical procedure. Inaccordance with various embodiments, information or data to assist inthe determination of the appropriate RF energy and manner to deliver theRF energy is supplied or obtained externally from the generator. Theexternal source in various embodiments is one or more memory modulesthat may be included with the electrosurgical instrument or viaconnections therebetween (wired or wireless) or via a separate tool,accessory and/or adapter and/or connections therebetween and/or via aseparate port or connection to the generator. The generator retrievesand/or receives the data and utilizes the data to command or operate thegenerator to determine and supply the appropriate RF energy in theappropriate manner.

Generally, in accordance with various embodiments, a bipolarelectrosurgical fusion instrument or tool is provided that is arrangedto fuse tissue captured between jaws. The jaws extend from an elongateshaft coupled to an actuator. The actuator is user accessible by which auser can manipulate the jaws to open and close the jaws and change theirorientation or position. A user through the actuator can also initiatefusion of issue in contact with the jaws. The jaws in variousembodiments includes an electrode on each jaw that are capable of beingconnected to an electrosurgical energy source, such as anelectrosurgical generator, to conduct radio frequency (RF) energytherebetween and the tissue captured between the jaws. A movable bladeis also provided to cut tissue captured between the jaws. In accordancewith various embodiments, at least one jaw includes at least oneconductive post that is positioned between the blade and an electrode ofthat jaw. The conductive post is made of the same conductive material asthe electrodes of the jaws, but unlike the electrodes is not connectedor capable of being connected to an electrosurgical generator to conductRF energy therebetween. The conductive post however in accordance withvarious embodiments may participate in conducting electrosurgical energybetween the jaws and the tissue therebetween.

Referring to FIGS. 1-2 , an exemplary embodiment of electrosurgicalsystem is illustrated including an electrosurgical generator 10 and aremovably connectable electrosurgical instrument 20. The electrosurgicalinstrument 20 can be electrically coupled to the generator via a cabledconnection 30 to a tool or device port 12 on the generator. Theelectrosurgical instrument 20 may include audio, tactile and/or visualindicators to apprise a user of a particular predetermined status of theinstrument such as a start and/or end of a fusion or cut operation. Inother embodiments, the electrosurgical instrument 20 can be reusableand/or connectable to another electrosurgical generator for anothersurgical procedure. In some embodiments, a manual controller such as ahand or foot switch can be connectable to the generator and/orinstrument to allow predetermined selective control of the instrumentsuch as to commence a fusion or cut operation.

In accordance with various embodiments, the electrosurgical generator 10is configured to generate radiofrequency (RF) electrosurgical energy andto receive data or information from the electrosurgical instrument 20electrically coupled to the generator. The generator 10 in oneembodiment outputs RF energy (375 VA, 150 V, 5 A at 350 kHz) and in oneembodiment is configured to calculate a phase angle or differencebetween RF output voltage and RF output current during activation orsupply of RF energy. The generator regulates voltage, current and/orpower and monitors RF energy output (e.g., voltage, current, powerand/or phase). In one embodiment, the generator 10 stops RF energyoutput under predefine conditions such as when a device switch isde-asserted (e.g., fuse button released), a time value is met, and/oractive phase angle and/or change of phase is greater than or equal to aphase and/or change of phase stop value.

The electrosurgical generator 10 comprises two advanced bipolar toolports 12, a standard bipolar tool port 16, and an electrical power port14. In other embodiments, electrosurgical units can comprise differentnumbers of ports. For example, in some embodiments, an electrosurgicalgenerator can comprise more or fewer than two advanced bipolar toolports, more or fewer than the standard bipolar tool port, and more orfewer than the power port. In one embodiment, the electrosurgicalgenerator comprises only two advanced bipolar tool ports.

In accordance with various embodiments, each advanced bipolar tool port12 is configured to be coupled to electrosurgical instrument having anattached or integrated memory module. The standard bipolar tool port 16is configured to receive a non-specialized bipolar electrosurgical toolthat differs from the advanced bipolar electrosurgical instrumentconnectable to the advanced bipolar tool port 12. The electrical powerport 14 is configured to receive or be connected to a direct current(DC) accessory device that differs from the non-specialized bipolarelectrosurgical tool and the advanced electrosurgical instrument. Theelectrical power port 14 is configured to supply direct current voltage.For example, in some embodiments, the power port 14 can provideapproximately 12 Volts DC. The power port 14 can be configured to powera surgical accessory, such as a respirator, pump, light, or anothersurgical accessory. Thus, in addition to replacing electrosurgicalgenerator for standard or non-specialized bipolar tools, theelectrosurgical generator can also replace a surgical accessory powersupply. In some embodiments, replacing presently-existing generators andpower supplies with the electrosurgical generator can reduce the amountof storage space required on storage racks cards or shelves in thenumber of mains power cords required in a surgical workspace.

In one embodiment, connection of a non-specialized bipolar tool into thestandard bipolar port will not cause the generator to actively check thetool. However, the generator recognizes a connection so that theinformation of the non-specialized bipolar tool can be displayed. Inaccordance with various embodiments, the generator recognizes deviceconnection status for each of the advanced tool ports 12 andauthenticates connected devices before accepting RF energy activationrequests (e.g., activation of an instrument switch such as a fusebutton). The generator in one embodiment reads authenticated data fromthe connected device and reads electrical control values (such as butnot limited to voltage level settings, current level settings, powerlevel settings, active phase angle level settings, RF energy outputactivation timing limits, instrument short limits, instrument openlimits, instrument model/identification, RF energy output lineconfigurations, switch state command configurations and/or combinationsthereof) from the authenticated and connected device.

In accordance with various embodiments, the electrosurgical generator 10can comprise a display 15. The display can be configured to indicate thestatus of the electrosurgical system including, among other information,the status of the one or more electrosurgical instruments and/oraccessories, connectors or connections thereto. In some embodiments, thedisplay can comprise a multi-line display capable of presenting text andgraphical information such as for example an LCD panel display, which,in some embodiments can be illuminated via backlight or sidelight. Insome embodiments, the display can comprise a multi-color display thatcan be configured to display information about a particular instrumentelectrically coupled to the electrosurgical generator and a color thatcorresponds to a particular surgical procedure (such as, for examplecutting operations displayed in yellow text and graphics, fusion orwelding operations displayed in purple, and coagulation displayed inblue, bloodless dissection operations can be displayed in yellow andblue).

In some embodiments, the display can be configured to simultaneouslyindicate status data for a plurality of instruments electrically coupledto the electrosurgical generator and/or be portioned to display statusinformation for each instrument connected to a corresponding tool port.A visual indicator such as a status bar graph can be used to illustratea proportion of total available electrical energy to be applied to thebipolar electrosurgical instrument when actuated. In variousembodiments, an electrosurgical instrument operable to cut, coagulate,or fuse tissue could have three color-coded displays or bar graphs. Insome embodiments, a user can toggle the display between presentingstatus of multiple electrically connected instruments and status of asingle electrically connected instrument. In accordance with variousembodiments, once an instrument and/or accessory is connected and/ordetected a window opens in the user interface display showing the typeof instrument connected and status.

The electrosurgical generator in accordance with various embodiments cancomprise a user interface such as, for example a plurality of buttons17. The buttons can allow user interaction with the electrosurgicalgenerator such as, for example, requesting an increase or decrease inthe electrical energy supplied to one or more instruments coupled to theelectrosurgical generator. In other embodiments, the display 15 can be atouch screen display thus integrating data display and user interfacefunctionalities. In accordance with various embodiments, through theuser interface, the surgeon can set a voltage setting by the selectionof one to three levels. For example, at level 1, voltage is set to 110V; at level 2, voltage is set to 100 V; and at level 3, voltage is setto 90 V. Current is set to 5 Amps and power is set to 300 VA for allthree levels. In other embodiments, the voltage is preset or defaults toa specific level such as level 2. In other embodiments, like the currentand power settings, the voltage setting is not user adjustable tosimplify operation of the generator and as such a predetermined defaultvoltage setting is utilized, e.g., voltage is set to 100 V.

In one embodiment, the electrosurgical tool or instrument 20 can furthercomprise of one or more memory modules. In some embodiments, the memorycomprises operational data concerning the instrument and/or otherinstruments. For example, in some embodiments, the operational data mayinclude information regarding electrode configuration/reconfiguration,the instrument uses, operational time, voltage, power, phase and/orcurrent settings, and/or particular operational states, conditions,scripts, processes or procedures. In one embodiment, the generatorinitiate reads and/or writes to the memory module.

In one embodiment, each advanced bipolar electrosurgical instrumentcomes with a memory module and/or an integrated circuit that providesinstrument authentication, configuration, expiration, and logging.Connection of such instruments into the receptacles or ports initiatesan instrument verification and identification process. Instrumentauthentication in one embodiment is provided via a challenge-responsescheme and/or a stored secret key also shared by the generator. Otherparameters have hash keys for integrity checks. Usages are logged to thegenerator and/or to the instrument integrated circuit and/or memory.Errors in one embodiment can result in unlogged usage. In oneembodiment, the log record is set in binary and interpreted with offlineinstruments or via the generator.

In one embodiment, the generator uses time measurement components tomonitor a instrument’s expiration. Such components utilize pollingoscillators or timers or real-time calendar clocks that are configuredat boot time. Timer interrupts are handled by the generator and can beused by scripts for timeout events. Logging also utilizes timers orcounters to timestamp logged events.

In accordance with various embodiments, the generator provides thecapability to read the phase difference between the voltage and currentof the RF energy sent to the connected electrosurgical instrument whileRF energy is active. While tissue is being fused, phase readings areused to detect different states during the fuse process.

In one embodiment, the generator logs usage details in an internal logthat is down loadable. The generator has memory for storage of code andmachine performance. The generator has reprogrammable memory thatcontains instructions for specific instrument performance. The memoryfor example retains a serial number and instrument use parameters. Thegenerator stores information on the type of instruments connected. Suchinformation includes but is not limited to an instrument identifier,e.g., a serial number of a connected instrument, along with a timestamp, number of uses or duration of use of the connected instrument,power setting of each and changes made to the default setting. Thememory in one embodiment holds data for about two months, about 10,000instrument uses or up to 150 logged activations and is configured tooverwrite itself as needed.

The generator in accordance with various embodiments does not monitor orcontrol current, power or impedance. The generator regulates voltage andcan adjust voltage. Electrosurgical power delivered is a function ofapplied voltage, current and tissue impedance. The generator through theregulation of voltage can affect the electrosurgical power beingdelivered. However, by increasing or decreasing voltage, deliveredelectrosurgical power does not necessarily increase or decrease. Powerreactions are caused by the power interacting with the tissue or thestate of the tissue without any control by a generator other than by thegenerator supplying power.

The generator once it starts to deliver electrosurgical power does socontinuously, e.g., every 150 ms, until a fault occurs or a specificphase parameter is reached. In one example, the jaws of theelectrosurgical instrument can be opened and thus compression relievedat any time before, during and after the application of electrosurgicalpower. The generator in one embodiment also does not pause or wait aparticular duration or a predetermined time delay to commencetermination of the electrosurgical energy.

In one embodiment, an electrosurgical process such as a tissue fusionprocess starts with depressing a switch on the instrument or tool (51),which starts an initial measurement sequence as illustrated in FIG. 3 .With engagement of a switch on the tool, the generator takes initialmeasurements on the tissue (opens, shorts, etc.) (52) and based on theinitial measurements initiates or does not initiate the supply of RFenergy (53). In accordance with various embodiments, the generatormeasures tool and/or tissue impedance and/or resistance, and/or if aphase angle is within an acceptable range. In one embodiment, thegenerator performs a measurement of tissue between the electrodes of anelectrosurgical instrument connected to the generator utilizing RFenergy with a low energy range (e.g., a voltage about 1-10 Volts) thatdoes not cause a physiological effect (i.e., a passive measurement). Invarious embodiments, the generator uses the initial impedancemeasurement to determine if the instrument is shorted, faulty, open andthe like. Based on a positive result of the initial check, the generatorswitches-in a supply of RF energy from the generator to theelectrosurgical instrument and ultimately to the tissue (54). After RFpower is turned on and is being supplied continuously by the generator,the generator monitors the phase angle or difference and/or change ofphase angle between current and voltage of the supplied RF energy (55).

At or upon a predefined point, condition or threshold (56), the supplyof RF energy is terminated (57). In this case, an acoustical and/orvisual signal is provided indicating that the tissue is fused (or thatan error has occurred (e.g., shorting of the electrodes) and/or anunexpected condition has occurred (e.g., permissible although unexpectedswitch release)). In accordance with various embodiments, the predefinedpoint, condition or threshold and/or initialization checks aredetermined based on an instrument algorithm or script provided for aconnected electrosurgical instrument, procedure or preference. Inaccordance with various embodiments, the product of measured tissuepermittivity and conductivity or an initial phase shift is utilized todetermine the end point for a connected instrument.

Referring now to FIGS. 4-1 , in one embodiment, the electrosurgicalgenerator 10 is connected to AC main input and a power supply 41converts the AC voltage from the AC main input to DC voltages forpowering various circuitry of the generator. The power supply alsosupplies DC voltage to an RF amplifier 42 that generates RF energy. Inone embodiment, the RF amplifier 42 converts 100 VDC from the powersupply to a sinusoidal waveform with a frequency of 350 kHz which isdelivered through a connected electrosurgical instrument. RF sensecircuitry 43 measures/calculates voltage, current, power and phase atthe output of the generator in which RF energy is supplied to aconnected electrosurgical instrument 20. The measured/calculatedinformation is supplied to a controller 44.

In one embodiment, the RF sense analyzes the measured AC voltage andcurrent from the RF amplifier and generates DC signals for controlsignals including voltage, current, power, and phase that are sent tothe controller for further processing. In one embodiment, RF sensecircuitry 43 measures the output voltage and current and calculates theroot means square (RMS) of the voltage and current, apparent power ofthe RF output energy and the phase angle between the voltage and currentof the RF energy being supplied through a connected electrosurgicalinstrument. In particular, the voltage and current of the output RFenergy are processed by analog circuitry of the RF sense to generatereal and imaginary components of both voltage and current. These signalsare processed by an FPGA to give different measurements relating tovoltage and current, including the RMS measurements of the AC signals,phase shift between voltage and current, and power. Accordingly, in oneembodiment, the output voltage and current are measured in analog,converted to digital, processed by an FPGA to calculate RMS voltage andcurrent, apparent power and phase angle between voltage and current, andthen are converted back to analog for the controller.

Referring now also to FIGS. 4-2 , for each device port 45 a, 45 b thereare a pair of signals for voltage and a pair of signals for current thatoriginate from the RF amplifier 42. In one embodiment, the generator hastwo redundant RF sense circuits 43 a, 43 b that measures voltage andcurrent for each device at different locations on the RF amplifier. Thefirst RF Sense circuit senses current 145 a, 145 b by sense resistor141, 142, delivered through a connected electrosurgical instrument oneither device port 1 or device port 2, and the voltage 148 a, 148 bmeasured across return to output on either device port 1 or device port2. The second RF Sense circuit senses current 147 a, 147 b by senseresistor 143, 144, returned from a connected electrosurgical instrumenton either device port 1 or device port 2, and the voltage 146 a, 146 bmeasured across output to return on either device port 1 or device port2. The voltage input signals are high voltage sinusoidal waveforms at350 kHz that are attenuated and AC coupled by a voltage divider and aninverting filter to remove DC bias on the signals. An inverting filteris used as the voltage and current inputs are 180 degrees out of phaseas they are measured at opposite polarities. For each voltage inputsignal, two separate inverted and non-inverted voltage sense signals aregenerated. In one embodiment, a differential voltage measurement is madebetween the current input signals to generate two separate pairs ofinverted and non-inverted current sense signals. The current inputsignals represent voltage across a shunt resistor on the RF Amplifier inwhich this voltage is proportional to the current flowing through theshunt resistor. The current input signals are low voltage sinusoidalwaveforms at 350 kHz that are amplified using a non-inverting filter toremove DC bias on the signals. The RF Sense generates a signal that isanalogous to multiplying each voltage and current signal bypredetermined reference signals. As such, the RF Sense provides thenon-inverted voltage and current sense signals when the waveform ispositive, the inverted voltage and current sense signals when thewaveform is negative, and a ground signal when the waveform is zero.

The RF sense in accordance with various embodiments receives fourreference synchronization signals supplied by the controller via the RFamplifier. The synchronization signals are 350 kHz pulse signals withthe same duty cycle but with differing phase shifts and in oneembodiment are 90 degrees phase shifted from each other. Two of thesynchronization signals are used to generate the in-phase waveforms togenerate the real component of the input waveforms and the two othersynchronization signals are used to generate the quadrature waveforms togenerate the imaginary components of the input waveforms. These signalsare processed further to generate control signals to a plurality ofswitches. The outputs of the switches are tied together to generate asingle output. In one embodiment, the control signals to the switchesdetermine which input signal passes through to the single output. Inaccordance with various embodiments, a first combination allowsnon-inverted voltage and current sense signals to pass through whichrepresents or is analogous to multiplying these sense signals by apositive pulse. A second combination allows the inverted voltage andcurrent sense signals to pass through which represents or is analogousto multiplying these sense signals by a negative pulse. A thirdcombination allows the ground signal to pass through generating a zerovoltage output which represents or is analogous to multiplying the sensesignals by zero. Each output is supplied to a low pass filter thatgenerates a DC voltage corresponding to the real or imaginary componentof the sensed signals. These signals supplied to ADCs which sends adigital signal to the FPGA.

In one embodiment, Controller 44 controls the RF amplifier 42 to affectthe output RF energy. For example, Controller utilizes the informationprovided by the RF sense 43 to determine if RF energy should beoutputted and when to terminate the output of RF energy. In oneembodiment, the controller compares a predetermined phase thresholdbased on a particular tissue in contact with the connectedelectrosurgical device 20 to determine when to terminate the output ofRF energy. In various embodiments, the controller performs a fusionprocess described in greater detail below and in some embodiments thecontroller receives the instructions and settings or script data toperform the fusion process from data transmitted from theelectrosurgical instrument.

In accordance with various embodiments as shown in FIGS. 4-2 , thegenerator has six major sub-systems or modules of circuitry that includeSystem Power or Power Supply 45, Controller 44, Front Panel Interface46, Advanced Bipolar Device Interface 47, RF Amplifier 42 and RF Sense43. In accordance with various embodiments, one or more of the circuitrymay be combined or incorporated with other circuitry. The Power supply45 is configured to provide DC voltages to all the other circuitry orsub-systems along with control signals to control the power supplyoutputs. The power supply receives AC power input that is 90 - 264 VAC,47 - 63 Hz and in one embodiment the power supply has a switch,integrated or separate, that is configured to connect or disconnect theAC power input from the generator. The controller through the FrontPanel Interface (FPI) and Advanced Bipolar Device Interface (ABDI)supports the user interface 21 and instrument connections forelectrosurgical devices 1 and 2 connected to the electrosurgicalgenerator.

The RF Amplifier 42 generates high power RF energy to be passed througha connected electrosurgical instrument and in one example, anelectrosurgical instrument for fusing of tissue. The RF Amplifier inaccordance with various embodiments is configured to convert a 100 VDCpower source to a high power sinusoidal waveform with a frequency of 350kHz which is delivered through the ABDI 47 and eventually the connectedelectrosurgical device. The RF Sense 43 interprets the measured ACvoltage and current from the RF amplifier 42 and generates DC controlsignals, including voltage, current, power, and phase, that isinterpreted by Controller 44.

The generator has a plurality of specialized connection receptacles, inthe illustrated embodiment device port 1 and device port 2, that areused only for connecting to advanced bipolar devices, such as theelectrosurgical fusion instrument described in greater detail below. Thespecialized receptacles each include an array spring-loaded probes orpogo pins. The generator in various embodiments includes a circuit todetect the presence of an advanced bipolar device prior to energizingany active output terminals at the receptacles.

The Front Panel Interface (FPI) 46 is configured to drive a display,device signals from the controllers and LED backlights for front panelbuttons. The FPI is also configured to provide power isolation throughregulators and provide functionality for the front panelswitches/buttons. In one embodiment, the ABDI 47 is used as apass-through connection which provides a connection to the devicesthrough the FPI. The FPI also provides connection between Controller 44and a connected electrosurgical device through the ABDI. The deviceinterface in one embodiment is electrically isolated from the rest ofthe FPI. The interface in various embodiments includes lines that readand write to an FRAM on an advanced bipolar device, read a triggerswitch and/or read a signal that indicates a device is connected. In oneembodiment, a device memory circuit is provided that utilizes thecontroller’s SPI interface to read and write the FRAM of the advancedbipolar device. In one embodiment, the FRAM is replaced with amicrocontroller and the interface includes an interrupt line so allinformation passed through a digital interface between theelectrosurgical device and the generator. FPI provides isolation for SPIsignals to and from advanced bipolar device through ABDI. In oneembodiment, the SPI interface is shared between two advanced bipolardevices with port pins being used as chip selects.

In accordance with various embodiments, the generator includes a SPIcommunication bus that allows the controller to have bi-directionalcommunication with the CPLDs and the RF Sense FPGAs. In variousembodiments, the FPI provides SPI interface between the controller andconnected devices through an ABDI connector to communicate with the FRAMon the advanced bipolar devices. FPI also provides electrical isolationfor low voltage signals from between controller and the ABDI. The deviceinterface on the ABDI is configured to transmit RF energy to theconnected device along with SPI communication. In one embodiment, theABDI connects a signal from a device that indicates it is connected.

The FPI-ABDI interface provides power to the devices that connect to thegenerator, SPI communication between controller and the devices, deviceswitch signals from the devices to the controller, and device connectedsignals from the devices to the controller. ABDI provides the RF energyto each connected advanced bipolar device through a separate pogo pinarray. The FPI provides signal, low voltage power and high voltage RFpower from the FPI and RF Amplifier to the connected device through theABDI connector via the pogo pin array.

Referring now also to FIG. 5 , the RF amplifier comprises a transistorH-bridge circuitry in which pairs of transistors are switched on and offin accordance with a pulse width modulation signal from a pulse widthmodulation and fault detection circuitry 31 to generate a sinusoidalsignal from DC voltage supplied to the RF amplifier. The RF energy issupplied to the electrosurgical instrument via device ports 45. Thesinusoidal signal is filtered by filter circuitry 32 and communicated tothe connected and active electrosurgical instrument by switching andtissue measure circuitry 33. Voltage, current, power, phase and othermeasured/calculated information is determined by a voltage and currentsense circuitry 34 in conjunction with the RF sense 43. In oneembodiment, the generator includes a relay matrix which selectivelyswitches or steers the RF energy from the RF amplifier to one of thedevice ports. In one embodiment, the switching and tissue measurecircuitry 33 includes a low voltage network analyzer circuit used tomeasure instrument and/or tissue impedance before RF power is turned on.If successful, e.g., no short or open is detected for an electrosurgicaldevice, RF energy is switched and thus the RF amplifier 42 supplied RFenergy to one of the device ports 45.

The RF amplifier 42 in one embodiment receives voltage and current setpoints, which are input by the user through a user interface, to set theoutput level of the RF amplifier. The user sets points are translatedinto operating levels by digital to analog converters of the RFamplifier. The set points in one embodiment include a maximum voltageoutput, maximum current output, and a maximum power output. Inaccordance with various embodiments, the RF amplifier provides the RFenergy based on one or more of these set points, such as providing theoutput voltage of the RF amplifier so that one or more of the set pointsare not exceeded.

The RF Amplifier in accordance with various embodiments manages the DCto RF conversion process as well as certain system electricalmeasurements. Switching and tissue measure circuitry routes RFtransformers or measurement components to the output electrodes. Inaccordance with various embodiments, volt-ampere (VA) is the unit usedfor the apparent power provided by the generator and is equal to theproduct of root-mean-square (RMS) voltage and RMS current. In directcurrent (DC) circuits, this product is equal to the real power (activepower) in watts. Volt-amperes are useful in the context of alternatingcurrent (AC) circuits (sinusoidal voltages and currents of the samefrequency). Volt-amperes and watt have a dimension of power (time rateof energy), but are still different.

The controller FPGA has direct control of the RF output relays. Theoutput relay configuration determines which drive signal (RF or tissuemeasure) is routed to which device port, either device port 1 or 2 asshown in FIGS. 5-1 and 5-4 . During calibration they can also connect toa predetermined load, e.g., a resistor having a set value, across thetissue measure analyzer to calibrate it before connecting the deviceload (load of the connected electrosurgical instrument in contact withtissue). The RF output relays are located by or incorporated into the RFAmplifier 42.

In accordance with various embodiments, the controller generates a pairof Device 1 Relay control signals for Device 1 relay pair 61 to connectthe RF energy bus to the device 1 port. In a similar manner, thecontroller generates a pair of Device 2 Relay control signals for Device2 relay pair 62 to connect the RF energy bus to the device 2 port. TheRF Amplifier relay pair 63 controls whether the RF amplifier output isconnected to the RF energy bus and the Tissue Measure relay pair 64controls whether the Tissue Measure analyzer is connected to the RFenergy bus. The RF amplifier and Tissue Measure analyzer are sources tothe RF energy bus, and the device ports are destinations for theselected energy. The Tissue Measure Calibration relay 65 connects thepredetermined calibration load across the RF energy bus.

As such, in accordance with various embodiments are used to direct theflow of RF energy or the output of the tissue measurement circuit to oneof the device ports. Four pairs of relays signals control four pairs ofrelays that change the flow of energy through the system. A first relaypair allows for the high power RF signals to flow to the ABDI 47 andeventually through the connected device. A second relay pair allows forthe tissue measure circuit to send and measure signals from the devicesvia the ABDI. A third and fourth relay pair allow for the signal,whether being the high power RF signals or the tissue measure signals toflow to either Device 1 or Device 2 via the ABDI. The signals thatcontrol the relays are controlled by the Controller 44.

The calibration signal controls a fifth relay that allows the tissuemeasure circuit on the controller to measure a predetermined load 66.The input signals to the relay circuits, which are HIGH when the relaysare open, are inverted by inverters. The output to the inverters isconnected to MOSFETs, which controls the relay. When a relay must beclosed, the input to the relay circuit goes LOW, which causes the outputof the inverter, and thus the input to the MOSFET, to go HIGH. When theinput of the MOSFET is HIGH, this allows 5V to flow through the coil,closing the relay and allowing signals to pass through. The relays areopen and closed in a certain order or sequence, which is determined bythe controller.

In accordance with various embodiments, a Device 1 Active signal isasserted when the relays are configured for RF or Tissue Measure energyon device port 1, a Device 2 Active signal is asserted when the relaysare configured for RF or Tissue Measure energy on device port 2, andDevice 1 and Device 2 RF On signals are active only when the RFamplifier is ON and the relays are in the RF Energy on Device 1 or RFEnergy on Device 2 configurations, respectively.

The controller FPGA controls the RF amplifier based on settings providedby the microcontroller. In one embodiment, the settings from themicrocontroller are set by a script file retrieved from memory attachedto a connected electrosurgical instrument. The microcontroller in oneembodiment sets the desired voltage, current and power levels andenables an RF amplifier output.

In one embodiment, a low power buffered voltage-out DAC provides the setvalues for Voltage, Current and Power to the control loop and erroramplifier. The control loop or system is illustrated in FIG. 5-5 . Thevoltage, current, and power feedback voltages 84, 85 and 86 go through afilter which is shown as a gain stage 87. This filtered feedback issummed 88 with respective set point parameters and each error is thenintegrated through a circuit 89 that was tuned for each parameter. Allof the error outputs junction together with diodes 80 so that the lowestoutput controls the PWM circuit 90.

Each of the low-passed voltage, current and power feedback signal andthe inverted set voltage, current and power signals (VSET 81, ISET 82,and PSET 83) pass through a resistor and combine together to make asignal with amplitude of (FVltFBT - Vset)/2, (FCurFBT -Iset)/2, and(FPwrFBT - Pset)/2 which are considered as an error signal in eachcontrol loop. The next stage is a proportional-integral controller (PI)that produces a DC signal (VError, IError, PError) as the result oferror signal changes at its input. VError, IError, PError are used at asumming junction to define which one of voltage, current or power are inthe control of the main control loop to force certain PWM duty cycle forRF amplifier 42.

Referring also now to FIG. 6 , RF sense 43 comprises a synchronousdetector that samples the RF energy being supplied to theelectrosurgical instrument. The RF sense removes unwanted harmonics ofthe RF energy by multiplying the supplied RF energy to a referencesignal or signals. From the signal product, the RMS voltage, RMScurrent, apparent power and phase information can be calculated. The RFsense includes ADC circuitry 36, isolation components 37, an FPGA 38 anda DAC 39. Real and imaginary components of raw current and voltage dataare determined via the Analog to Digital circuits and these componentsthat provided to an FPGA 38 via isolation barriers or components 37 forprocessing of the components. In the illustrated embodiment, two devicechannels are provided for two advanced bipolar electrosurgical toolports and the associated instruments. Fault detection data 35 issupplied via the FPGA 38 and digital forms of measured or calculatedvoltage, current, power and phase are provided by the DAC circuitry 39.In one embodiment, the FPGA is responsible for signal conditioning offeedback signals from the synchronous detector and is also responsiblefor detecting faults.

The ADCs 36 simultaneously sample the output of the synchronousdetector, which represent the real and imaginary values for the voltageand current of the output signal on each device port. After they sample,the FPGA stores these values in an ADC control module. An ADC errorcorrection module pulls this data from the ADC control module via amultiplexer to correct sample errors by applying offset and gaincorrections.

The output of the ADC error correction module is a representation of thereal and imaginary components of voltage and current from both an activeand inactive device port. The output of the ADC correction module alsooutputs a sign bit for each signal from the active device port for phasecalculation. A separate module takes the real and imaginary values forthe voltage and current from the active device port and computes the RMSvoltage, RMS current, and apparent power magnitudes and the phasebetween voltage and current. Once these values are computed, the DACerror correction module applies offset and gain corrections to thescaled and signed representation of each signal. DAC error correctionfor voltage, current, power, and phase is done sequentially. The data issent to the DAC controller module. The DAC controller module sends outdata to the DACs.

The FPGA 38 monitors the real and imaginary values for voltage andcurrent and generates fault codes if their values deviate beyond aspecific threshold on the inactive device port. Additionally, if thephase relationship between the synchronization signals is lost, the FPGAwill generate a fault code. The synchronization monitor module has fourinputs that are always 180 degrees out of phase from each other. Thismodule monitors for valid time relationships between the signals andflags an error if there is a violation.

In accordance with various embodiments, the RF sense FPGA is configuredto correct for errors in RF feedback signals and calculate the magnitudeand phase of these signals. A synchronous detector of the RF Sense usessynchronization signals generated by the controller FPGA to generatein-phase (real) and quadrature (imaginary) components of the voltage andcurrent feedback signals from the RF Amplifier. The RF sense FPGAmonitors the phase relationship between synchronization signalsgenerated by the controller and asserts a fault when the phaserelationship is out of order.

In accordance with various embodiments, a plurality of synchronizationsignals are used as clock inputs for RF Sense. The synchronizationsignals have the same duty cycle and frequency. The only differencebetween the signals is their phase relationship. For example, in oneembodiment, a first synchronization signal is used as a reference andthe second synchronization signal is identical to first synchronizationsignal but is delayed by 180 degrees. A third synchronization signal isdelayed from first synchronization signal by 90 degrees and a fourthsynchronization signal is delayed from first synchronization signal by270 degrees. The clock edges provided by these four signals provide theexact timing required by the RF Sense for proper sampling of the RFoutput signal.

In accordance with various embodiments, the electrosurgical generatormeasures RF output voltage and current. Due to the electrosurgicalnature of the generator, however, it is required that the measurementsbe done using isolated circuitry. Voltage measurement can be simplebecause the signal to noise ratio is relatively high. Currentmeasurement using a current transformer however is problematic sincethere is a significant level of PWM output stage switching noise presentin the circuit and isolation of typical current transformer cannotsuppress this noise enough for the desired or required accuracy.Sampling the output voltage and current directly by using secondary sidereferenced (floating) Analog to Digital Conversion (ADC) and a shuntresistor can also create a different problem.

PWM switching noise is not harmonically related to the fundamental PWMcarrier frequency and has a wide bandwidth. This noise can be overcomeby significantly oversampling the signal in order to achieve a desiredor necessary accuracy. However, with a 350 kHz PWM carrier frequency, 64times over Nyquist sampling frequency and 12-bit resolution, therequired speed of the digital stream is 5.376×10⁸ bits/s, per ADCchannel. ADCs and digital isolators with this performance are difficultto source and relatively expensive.

In accordance with various embodiments, by using an accurate analogpreprocessor the frequency requirements for the digital stream can belowered. The analog preprocessor utilizes the fact that change of the RFoutput voltage and current in time is relatively slow and in general,the useful bandwidths of those signals are narrow.

In one embodiment, the analog preprocessor comprises a synchronousdetector which allows transfer of the RF signal spectrum from the areaconcentrated around the carrier frequency down to zero. The narrowedbandwidth significantly simplifies the complexity for the ADCs anddigital isolators. As such, ADC sampling frequency can be low anddigital isolator throughputs are reduced. Digital isolator couplingcapacitance is also reduced due to reduced or minimal number of parallelchannels. In general, processing speed requirements are reduced whichleads to lower cost components.

Referring to FIG. 6-1 to 6-4 , in accordance with various embodiments, asynchronous detector comprises an analog multiplier, which definesoverall accuracy of the circuit. However, due to the presence ofoff-band PWM noise and/or a 350 kHz carrier frequency existing analogmultipliers will not satisfy an accuracy requirement of 0.5% or better.

A local oscillator (LO), which is required for spectrum transform, canbe non-sinusoidal. If the number of gain levels present in such awaveform is limited, an analog multiplier can be implemented usinganalog switches instead of a multiplier.

In one embodiment, as shown in FIG. 6-1 to 6-2 , the LO waveform 95, 96utilized is a square wave where gain 91, 92 can be either +1 or -1. Lowpass filters (LPF) 93, 94 at the outputs of switches are used foraveraging and to suppress conversion components with high frequencies.The input signal 97 of the synchronous detector can be defined as thefundamental frequency:

$\omega = \frac{2\pi}{T}$

where T is defined as the fundamental period, A is the fundamentalamplitude and p is the fundamental phase. The 3^(rd) harmonic frequencycan be defined as:

$3\omega = \frac{6\pi}{T}$

where kA is defined as the amplitude of the 3^(rd) harmonic frequency, kis the ratio of the 3^(rd) harmonic amplitude over fundamental, and q isthe phase of the 3^(rd) harmonic frequency. Real (Re) and Imaginary (Im)output voltages of the synchronous detector are as follows:

$\begin{array}{l}{Re = \frac{A}{T}\{ {- {\int_{- \frac{T}{2}}^{- \frac{T}{4}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )dt +}}} )} \\{\int_{- \frac{T}{4}}^{\frac{T}{4}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )dt -}} \\{( {\int_{\frac{T}{4}}^{\frac{T}{2}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )dt}} ) =} \\{\frac{A}{6\pi}( {- 3\mspace{6mu}\sin p + 3\mspace{6mu}\cos p - k\sin q - k\cos q} ) +} \\{\frac{A}{6\pi}( {6\cos p - k\cos q} ) + \frac{A}{6\pi}( {3\sin p + 3\cos p + k\sin q - k\cos q} ) =} \\{\frac{A}{2\pi}( {4\cos p - k\cos q} )}\end{array}$

$\begin{array}{l}{Im = \frac{A}{T} = \{ {- {\int_{- \frac{T}{2}}^{0}( {\cos( {\frac{2\pi\text{t}}{\text{T}}\text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )}dt +} )} \\{( {{\int_{0}^{\frac{T}{2}}( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )}dt} ) = \frac{A}{3\pi}( {- 3\sin p - k\cos q} ) +} \\{\frac{A}{3\pi}( {- 3\sin p - k\cos q} ) = - \frac{A}{3\pi}( {6\sin p + 2k\sin q} )}\end{array}$

In the case that only the fundamental frequency is present in the inputsignal spectrum (k = 0), complex amplitude can be calculated as follows:

$Mod = \frac{2A}{\pi}$

$Arg = Atan\frac{- \sin p}{\cos p}$

If the amplitude of the 3^(rd) harmonic is not equal to the zero, thecomplex amplitude can have a different result.

Referring now to FIG. 6-3 to 6-4 , in accordance with variousembodiments, a complex LO 3-level waveform 98, 99 generated by a 3-levelwaveform local oscillator can be used. By using the LO 3-level waveform,real and imaginary output voltages become independent on the presence ofthe 3^(rd) harmonic, but can be distorted if higher order harmonics arepresent. Real (Re) and Imaginary (Im) output voltages of the synchronousdetector are as follows:

$\begin{array}{l}{Re = \frac{A}{T}\{ {- {\int_{- \frac{T}{2}}^{- \frac{T}{3}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )dt +}}} )} \\{\int_{- \frac{T}{6}}^{\frac{T}{6}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )dt -}} \\{( {\int_{\frac{T}{3}}^{\frac{T}{2}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )dt}} ) =} \\{\frac{A}{12\pi}( {- 3\mspace{6mu}\sin p + 3\mspace{6mu} \sqrt{}3\cos p - 4k\sin q } ) + \frac{A \sqrt{}3 }{2\pi}\cos p +} \\{\frac{A}{6\pi}( {3\sin p + 3\cos( {p + \frac{\pi}{6}} ) + 2k\sin q} )}\end{array}$

Because

$\cos( {\text{p+}\frac{\pi}{6}} ) = \frac{1}{2}(  \sqrt{}3\cos\text{p-sin p}  )$

then

$\begin{array}{l}{\frac{\text{A}}{6\pi}( {3\sin\text{p + 3 cos}( {\text{p+}\frac{\pi}{6}} ) + 2\text{k sin q}} ) =} \\{\frac{\text{A}}{12\pi}( {6\,\,\sin\,\text{p +} \sqrt{}\text{3}\,\text{cos}\,\text{p-sin}\,\text{p +2k sin q} } )}\end{array}$

and

$Re = \frac{A \sqrt{}3 }{\pi}\cos p$

$\begin{matrix}{{Im} = \frac{\text{A}}{\text{T}}\{ {\text{-}{\int_{- \frac{5\text{T}}{12}}^{- \frac{\text{T}}{12}}{( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + q} )} )\text{dt +}}}} )} \\{\int_{\frac{\text{T}}{12}}^{\frac{\text{ST}}{12}}{( {( {\cos( {\frac{2\pi\text{t}}{\text{T}} + \text{p}} ) + \text{k cos}( {\frac{6\pi\text{t}}{\text{T}} + \text{q}} )} )\text{dt}} )\text{=}}} \\{\text{-}\frac{\text{A} \sqrt{}\text{3} }{2\pi}\sin\,\text{p -}\frac{\text{A} \sqrt{}\text{3} }{2\pi}\sin\,\text{p} = \text{-}\frac{\text{A} \sqrt{}\text{3} }{2\pi}\sin\,\text{p}}\end{matrix}$

In this case, the complex amplitude is as follows:

$Mod = \frac{A \sqrt{}3 }{\pi}$

$Arg = Atan\frac{- \sin p}{\cos p}$

Therefore, the dependence on the presence of 3^(rd) harmonic of anylevel is eliminated. In accordance with various embodiments, thesymmetrical nature of a RF amplifier creates signals with naturally lowlevels of even harmonics. Low pass filters in one embodiment alsosuppresses high frequency PWM carrier components and is capable ofsuppression of 5th harmonics to sufficiently low levels. Furtherexamples of the synchronous detector’s operation are provided byexemplary signal waveforms at the respective outputs (SynchDetRe andSynchDetIm) prior to filtering by the low pass filter 93 for anexemplary input signal (Uin = cos ωt) are also shown in FIG. 6-5 to 6-6. FIGS. 6-7 provides an exemplary signal waveform illustrating an inputsignal phase shifted (e.g., Uin = cos(ωt + π/4)) and likewise exemplarysignal waveforms at the respective outputs (SynchDetRe and SynchDetIm)prior to filtering by the low pass filter 93 for such an input signalare shown in FIG. 6-8 to 6-9 . FIGS. 6-10 provides an exemplary inputsignal that is significantly corrupted but has no harmonics higher than4^(th) harmonics and likewise exemplary signal waveforms at therespective outputs (SynchDetRe and SynchDetIm) prior to filtering by thelow pass filter 93 for such an input signal are shown in FIG. 6-11 to6-12 . As such, as illustrated, the synchronous detector in accordancewith various embodiments can accurately recover the fundamentalamplitude and phase of such input signals and thus accurately provideReal (Re) and Imaginary (Im) output voltages for the detection andmeasurements or calculations of phase and/or rate of changes of phase.

Referring now to FIGS. 7 and 8 , the controller 44 includes RF smootheror smoothing modules or circuitry 68 to remove noise and/or extrapolatea smooth modulated DC signal representative of the RF energy beingoutputted (e.g., voltage, current, power and/or phase). An exemplary RFenergy before and after the RF smoother are shown in FIGS. 19-20 . Inone embodiment, a data sampler 69 collects raw, evenly spaced datavalues from the analog to digital (ADC) phase, voltage, current, andpower channels as the measurements are taken, then the RF smoother 68applies a smoothing algorithm to filter the raw values into theresulting smoothed values. Further analysis is performed to determinevarious points of interest or events, such as the phase minimum and zerocrossing points. Those points of interest are passed to the eventhandler 67 to trigger state changes. The generator in one embodimentwaits for specific points of interest or events to be reached beforechanging states.

In one embodiment, the RF smoother 68 detects the local minimum point inthe smoothed phase data provided by the RF Smoother and this point ofinterest is passed to the event handler 67 that notifies the scriptoperations engine 65. In one embodiment, the RF smoother detects thezero crossing indicated for example by an ADC reading equal to abouthalf of the maximum ADC counts and this point of interest is passed tothe event handler that notifies the operations engine 65. Input andoutput commands, interrupts and event detections are provided by aquery/command interface 66.

In accordance with various embodiments, the operations engine 65 enablesthe generator to be configurable to accommodate different operationalscenarios including but not limited to different and numerouselectrosurgical instruments, surgical procedures and preferences. Theoperations engine receives and interprets data from an external sourceto specifically configure operation of the generator based on thereceived data.

The operations engine receives configuration data from a device databasescript file 101 that is read from a memory device on a device plug orkey 102. The script defines the state logic used by the generator. Basedon the state determined and measurements made by the generator, thescript can define or set output levels as well as shutoff criteria. Thescript in one embodiment includes trigger events or indicators thatinclude indications of short condition for example when a measured phaseis greater than 70 degrees or an open condition for example when ameasured phase is less than -50 degrees.

In one embodiment, the operations engine provides system states and userstates. System states are predefined states that control or managespecific predefined operations or operation conditions of the generator,such as successfully applying RF energy or indicating an error. Systemstates in one embodiment are a pre-defined set of configurations thatthe system can be in (e.g., idle vs. energized) and whose functions arehard-coded into the electrosurgical generator. For example, a RF Donestate is a system state that indicates that an RF energy cycle has beencompleted without errors. User states provide a framework through whichcustomized or specialized operations and values can be established bydirection from an external source for a particular instrument, procedureand/or preference.

In one embodiment, the script sets forth the system states and theirexit conditions, e.g., expiration times or directions to another stateand where the user states begin. For each user state, operationparameters for the specific state can be defined such as power, voltage,and current settings or are carried over from a previous state. In oneembodiment, the user states may provide device, operator or proceduralspecific states and in one embodiment, the user states may be providedfor testing or diagnostics specific states.

An exemplary two user state process is shown as an example in FIG. 10 .The process begins in a system state Idle (71). If the switch is pressed(asserted) (78), the generator transitions to the User State 1 (72).Based on the exit condition, the generator transitions to the nextstate, User State 2 (73) or one of the system states (e.g. RF_Done (74)or Error (75)). If there is no user state after User State 2, then theprocess transitions back to a system state other than the system stateIdle which will then transition the generator back to the system stateIdle.

The exit criteria or condition (79) for each state defines the logicpath for the script based on measurements made by the generator and thusthe generator transitions from user state to user state. However, if theexit condition does not match the expected logic path, the seal oroperation cycle is considered to have not been successfully completed,and the system state Error (75) is achieved. If the exit condition doesmatch the expected logic path or indicates completion of an operationcycle, the operation cycle is considered to have been completedsuccessfully, and the system state RF_done (74) is achieved. In oneembodiment, if the switch is released before the completion of the fusecycle, the system state Switch_Release (76) is achieved. In accordancewith various embodiments, additional system states can be predefined tohandle other general system errors or unexpected deviations from theexpected logic path such as a timeout state indicating a maximum time tocomplete a fuse or operation cycle has been exceeded. Additionally,although only two user states are shown, the generator is expandable andconfigurable to include additional user states to provide an expandedlogic path for a particular or a range of electrosurgical instruments,procedures and/or preferences.

Through the scripts, individual parameters or conditions pertaining tothe electrosurgical or fusion process may be set. For example,acceptable impedance levels for an electrosurgical instrument prior toRF energy activation, maximum voltage, current and power settings (andin one embodiment, for each corresponding user adjustable level settings(e.g., level 1-3)), switch assert and de-assert dwell times foractivation and deactivation, and stuck button error times at initialconnection and following the completion of an operation cycle.

In one embodiment, the operations engine provides at least 30 states, 5system states and 25 user states that provide the operational controlparameters and output characteristics. These characteristics define thevoltage, current and power output ranges that can be the full scale ofthe generator’s output ranges or any level below. Each state in oneembodiment has the ability to provide operation conditions such as toenable or disable RF output, modify the RF output regulation levels, aswell as recognize and act upon different events or control indicatorsbased on for example time, voltage, current, power, or phase (ϕ) orcombinations of these values and transition to another user state, errorstate, or completion state. The data, in one embodiment, that theoperations engine receives from the event handler or the RF smoother hasbeen smoothed according to a double exponential smoothing algorithm orexponential moving average algorithm. Voltage, current, power and phasesmoothing parameters can be set individually in the device script.

In one embodiment, every 1 ms, the data sampler reads and stores the ADCchannel measurements, e.g., voltage, current, power and phase angle.After the ADC measurements are processed, the data sampler calls the RFsmoother. The RF smoother smooths or filters the ADC measurements andthen notifies the event handler. If the event handler (checking forexample every 15 ms) finds that a specific event or indicator hasoccurred, the event handler notifies the operations engine 65. After theoperations engine has processed the event, it sets up the event handlerfor the next series of event evaluations.

The event handler in one embodiment is configured to evaluate a set ofscript events as defined by the device script. A script event is agrouping of postfix (Reverse Polish Notation (RPN)) tokens whichdescribe a Boolean equation. The operations engine 65 provides the eventhandler with a port corresponding to a device script database and with ascript state 68. The event handler evaluates that state and each eventin that state in which each event is described by a Boolean equation.The event handler calculates the value of the Boolean equation. If anyevent evaluation in the state is found to be true, the event handlernotifies the script operations engine, indicating that an event in theparticular state was encountered, and providing the next location in thedevice script database where the script is to continue execution. If noevent is found, then the event handler does not notify the scriptoperations engine. In one embodiment, the event handler is configured toevaluate up to 10 events per a given sample time in which events areevaluated sequentially.

The event handler obtains timer values from a system timer 70 and switchevents (press, release) 72 from a connected device and simulated switchevents from the diagnostic port 71. The event handler also checks fortime based events, such as a global timeout or state timeout and otherrecoverable errors such as over-voltage or over-current conditions. Inone embodiment, this check is done by reading and comparing various ADCvalues to limits set by the device script.

The operations engine in one embodiment receives and installs the devicescript database file into a predefined device script database storagelocation in memory. During script development, the script compilercompiles the script source file into the device script database,containing among other things event data stored in RPN notation andstate instructions. Prior to installation, the operations engine checksthe device script database, i.e., the compiled script, for errors. Inone embodiment, operations engine checks each token in the RPN data forvalues “out of range”, that a Boolean value is returned and that thereis only one RPN token remaining on the stack when the token count is atthe end of the RPN data.

Referring now to FIG. 9 , in accordance with various embodiments, adevice is plugged into the tool port of the generator. The operationsengine authenticates the device, which indicates that the integrity ofthe device memory and script has not been compromised. If the devicepasses authentication, the operations engine verifies the scriptdatabase, which indicates that the script database was built correctly.If the script database is verified as valid, the operations enginebegins script execution. (The start section of the IDLE state is set asthe row number in the script table to begin running at.)

In operation, the operations engine reads commands from the scriptdatabase. When the operations engine must wait for an event, theoperations engine instructs the event handler with which events toidentify and waits. When an event is identified by the event handler,i.e., event evaluation is true, the event handler notifies theoperations engine and the event handler is disabled from further eventevaluation for the tool port until the operations engine commands theevent handler again. In one embodiment, the event handler is interruptedfrom a timer at least once per 20 ms or from ADC data being to evaluateevents. The operations engine resumes execution when it is notified bythe event handler that an event has been triggered.

The fusion process could be terminated (a) at a fixed and absoluteresistance (for example 2k Ohms), which would neglect both the size andtype of tissue, (b) at a specific multiple of the time where the ohmicresistance is minimal, (c) at a specific multiple of the time where theohmic resistance is the same as the initial one, or (d) at a specificmultiple of the time where the ohmic resistance is a certain factor ofthe minimal one. However, considering burst pressure of fused arteriesand thermal spread, the termination of the fusion process is determinedto be in the flattened part of the impedance curve. As can be seen inFIGS. 12-20 , however, this region is also an inexact range forimpedance measurements. Similarly, each succession of (a) to (d) becomesbetter in determining the end-point of the fusion time (resulting in thehighest desired bursting pressure with the least desired thermalspread). Utilizing the ohmic resistance only as termination criterioncan lead to incomplete results. This can be more pronounced when fusingdifferently sized tissues (even of same nature).

In one aspect, the determination of the end-point of the fusion processis given by monitoring the phase shift of voltage and current during thefusion process. Unlike impedance, the phase shift changes much morepronounced at times where fusion of tissue completes, and hence offers amore sensitive control value than the impedance. However, for varioustypes of tissue, reaching a high end of the phase range can lead toexcessively long fusing times. Accordingly, as will be described ingreater detail below, the application of RF energy via anelectrosurgical generator in conjunction with the measuring ormonitoring of phase shift are provided to fuse vessels and tissue inaccordance with various embodiments of electrosurgical system.

As such, the instrument generating the seal, fusion or connection of thetissue provides atraumatic contact to the connecting tissue and providesenough burst pressure, tensile strength, or breaking strength within thetissue.

In one embodiment, the generator initially determines the initialinstrument impedance and/or capacitance (e.g., during plug-in of theinstrument connector to the electrosurgical generator), wheretolerances/changes in the instrument characteristics are then accountedfor in the tissue measurement and endpoint determination process. Thiscan allow for tissue measurement values which are independent of theohmic and capacitive values and/or tolerances of a specificelectrosurgical instrument.

Exemplary RF energy control process for the electrosurgical generatorand associated electrosurgical instrument for fusing tissue inaccordance with various embodiments are shown in FIGS. 11A-11B. In oneembodiment, RF energy is supplied by the generator through the connectedelectrosurgical instrument or tool (101). The generator monitors atleast the phase and/or change of phase of the supplied RF energy (102).If a phase zero crossing or polarity change from positive to negative ornegative to positive is encountered (103), a phase stop is determined(104). The phase stop in one embodiment includes a predefined phaseangle and/or change of phase angle based on a determined tissue propertysuch as size, permittivity, conductivity and/or applied voltage, currentand/or power. The generator continues to monitor at least the phaseand/or change of phase of the supplied RF energy (106). If the phasestop (105) is reached or exceeded, the process is done or terminationprocedures are initiated and/or RF energy supplied by the generator isstopped (107).

In one embodiment, prior to the start of the process, impedance ismeasured to determine a short or open condition through a low voltagemeasurement signal delivered to a connected electrosurgical instrument.In one embodiment, a passive impedance measurement is used to determineif the tissue grasped is within the operating range of theelectrosurgical instrument (e.g., 2-200 Ω). If the initial impedancecheck is passed, RF energy is supplied to the electrosurgicalinstrument. In one embodiment, voltage of the RF energy is applied (111)in a ramping fashion starting from 25% to at most 80% of a globalsetting or, in one embodiment, an user selected level (e.g., 27.5-88 Vfor level 1, 25.0-80 V for level 2 and 22.5 V-72 V for level 3).

Voltage and phase of the applied RF energy are continuously measured(112). When the phase measurement equals zero or transitions frompositive to negative (113), voltage at that point is held constant atthat voltage or at a predetermined voltage. In one embodiment, the zeroor polarity crossing is used to determine the size of the tissue andselect the appropriate path for completing the fusion cycle. In oneembodiment, the voltage level of the ramp at the zero-crossing is usedto determine the size of the tissue and then the appropriate path. Ithas been noted that the time taken to reach the phase zero-crossing canbe associated with or correlate to the amount of water or moisture beingremoved from the tissue at that point and the tissue size.

In accordance with various embodiments, if the voltage level is lessthan 50% of the selected level at the phase zero-crossing (e.g., level1: voltage < 55 V; level 2: voltage < 50 V; level 3: voltage < 45 V),tissue size is determined to be small (114). If the voltage level isless than 60% and greater than 50% of the selected level at thezero-crossing (e.g., level 1: 55 V < voltage < 66 V; level 2: 50 V <voltage < 60 V; level 3: 45 V < voltage < 54 V), tissue size isdetermined to be medium (115). If the voltage level is greater than orequal to 60% of the selected level at the zero-crossing (e.g., level 1:voltage ≥ 66 V; level 2: voltage ≥ 60 V; level 3: voltage ≥ 54 V),tissue size is determined to be large (116). Based on the tissue sizedetermination being medium or large, the voltage of the applied RFenergy is held constant at the level at the zero-crossing. In accordancewith various embodiments, based on the tissue size determination beingsmall, the voltage of the applied RF energy is set to a predefinedvoltage and in one embodiment is set to 22 V. The predefined voltage inone embodiment is less than the voltage level based on the tissue sizedetermination being medium or large.

If the monitored phase and/or change of phase equals or is less than theselected predetermined phase and/or change of phase, electrosurgicalenergy is stopped (121). In one embodiment, if the calculated phase doesnot reach this phase stop within a set time, e.g., three, three andquarter or 4 seconds, electrosurgical energy is stopped. In oneembodiment, if tissue size is determined to be small, the phase stopand/or change of phase stop is set to phase < -7.0° and/or change ofphase < -2.3°/s (117). An exemplary graphical representation of RFenergy successfully fusing tissue with a tissue size determined to besmall is shown in FIG. 12 . Also, as illustrated, phase 12 b is shownrelative to other tissue readings or indicators such as current 12 a,power 12 c, impedance 12 d, temperature 12 e, energy 12 f and voltage 12g. If tissue size is determined to be medium, the phase stop and/orchange of phase stop is set to phase < -23.0° and/or change of phase <-7.1°/s (118). An exemplary graphical representation of RF energysuccessfully fusing tissue with a tissue size determined to be small isshown in FIG. 13 . Also, as illustrated, phase 13 b is shown relative toother tissue readings or indicators such as current 13 a, power 13 c,impedance 13 d, temperature 13 e, energy 13 f and voltage 13 g. Iftissue size is determined to be large, the phase stop and/or change ofphase stop is set to phase < -32.0° and/or change of phase < -8.0°/s(119). An exemplary graphical representation of RF energy successfullyfusing tissue with a tissue size determined to be small is shown in FIG.14 . Also, as illustrated, phase 14 b is shown relative to other tissuereadings or indicators such as current 14 a, power 14 c, impedance 14 d,temperature 14 e, energy 14 f and voltage 14 g. Additionally, althoughshown in FIGS. 12-14 , in various embodiments, the generator isconfigured to not measure or calculate one or more of the indicators orreadings, e.g., temperature or energy, to reduce operational and powerparts, costs and consumptions of the generator. The additionalinformation or readings are generally provided or shown for contextpurposes.

In accordance with various embodiments, phase is monitored inconjunction with current for open and short events while RF energy isbeing applied and in one embodiment after phase and/or change of phasestop or endpoints is reached to evaluate or determine if a falseindication of fusion (caused by an open or short) has been reached.

In accordance with various embodiments, the generator is configured toprovide additional regulation of various parameters or functions relatedto the output of the RF energy, voltage, current, power and/or phase andthe operations engine is configured to utilize the various parameters orfunctions to adjust the output of RF energy. In one exemplaryembodiment, the control circuitry provides additional regulationcontrols for direct regulation of phase in which voltage, current and/orpower output would be adjusted to satisfy specified phase regulation setpoints provided by the operations engine.

In accordance with various embodiments, the generator utilizes themeasured values of voltage, power, current and/or phase, e.g., controlindicators, to recognize and act or perform operation conditions. Invarious embodiments, additional measurements or calculations based onthe measured values related to RF output regulation circuitry areprovided by the script or operations engine to recognize and act uponadditional or different events related to or trigger by the additionalmeasurements or calculations relative to other measurements orthresholds. The additional measurements in one embodiment include errorsignals in combination with a pulse width modulation (PWM) duty cycleused to regulate the output of voltage, current and/or power or othersimilar regulation parameters. Different or additional events orindicators that could be identified and triggered in various embodimentscould be transitions from one regulation control to another regulationcontrol (e.g. current regulation to power regulation).

In accordance with various embodiments, the generator provides orconducts calculations to directly measure the rate of change of voltage,current, power and/or phase. For example, FIG. 15 provides exemplarygraphical representation of phase 15 a of the RF energy in relation tochange of phase of RF energy 15 b. The generator in one embodiment basedon these calculations or direct measurements can recognize and act upondifferent events related to the RF output and electrical characteristicsof the tissue during a fuse cycle.

In accordance with various embodiments, the predetermined completionindicator can be varied or modified by the operations engine. In oneembodiment, during a given fuse cycle, a tone (or other indicator)sounds at a phase threshold that is determined to be equivalent to a 7psi (3 × systolic pressure) seal 161 and then RF energy continues to beapplied to the vessel to a phase threshold that is determined to beequivalent to a higher burst pressure (e.g. 20 psi) 163 at which pointRF energy is automatically terminated. An exemplary graphicalrepresentation of RF energy fusing tissue utilizing seal pressuredeterminations is shown in FIG. 16 . Also, as illustrated, phase 16 g isshown relative to other tissue readings or indicators such as voltage 16a, power 16 b, impedance 16 c, energy 16 d, temperature 16 e and current16 f. In accordance with various embodiments, instead of or in additionto phase angle being used as a predetermined completion indicator or forother thresholds, time, voltage, current and power as well asconditional combinations thereof could be used.

In one embodiment, the user can release the activation button at anytime between the initial tone and the end tone. This provides thesurgeon with some degree of control with regards to the amount of RFenergy is being applied to the tissue. For example, for thin,non-vascular tissue, a surgeon may release the button closer to theinitial tone rather than wait for a subsequent tone. Similarly, forlarger tissue, a surgeon may release the button much later than theinitial tone or closer to a subsequent or end of cycle tone to therebycontinue to apply RF energy longer.

In one embodiment, phase angle setting is user accessible andadjustable. By adding a phase level setting parameter, the phase triggerthresholds could be tied to percentages or a multiple (positive ornegative) of the phase threshold. As such, the user could adjust a fusecycle time, e.g., shorter and longer fuse cycles (e.g., Level 1 (171),Level 2 (172), and Level 3 (173)).

Level 1 Level 2 Level 3 Phase Setting 30 60 90 Phase endpoint determinedby script (e.g. 33%) 10° 20° 30°

An exemplary graphical representation of RF energy fusing tissueutilizing user adjusted phase levels 171, 172, 173 is shown in FIG. 17A.Also, as illustrated, phase 17 g is shown relative to other tissuereadings or indicators such as voltage 17 a, power 17 b, impedance 17 c,energy 17 d, temperature 17 e and current 17 f.

An additional way for providing alternate endpoints or alternative RFoutput delivery paths is to provide additional or alternative scriptlogic paths based on the output level settings. This could also adjust afuse cycle time, e.g., shorter or longer seal cycles that are useradjustable (e.g., Level 1 (175), Level 2 (176), and Level 3 (177)). Anexemplary graphical representation of RF energy fusing tissue utilizingadditional or user level adjusted script logic paths 175, 176, 177 isshown in FIG. 17B. Also, as illustrated, phase 17g1 is shown relative toother tissue readings or indicators such as voltage 17a1, power 17b1,impedance 17c1, energy 17d1, temperature 17e1 and current 17f1.Additionally, although shown in FIGS. 16-17B, in various embodiments,the generator is configured to not measure or calculate one or more ofthe indicators or readings, e.g., temperature or energy, to reduceoperational and power parts, costs and consumptions of the generator.The additional information or readings are generally provided or shownfor context purposes.

As provided in various embodiments, the operations engine provides theability for the generator to operate between two or more states 18 e.State transitions can be triggered by time, voltage, current, power orphase 18 a, 18 b, 18 d and could also be used for an exit state 18 c. Inone embodiment, keeping a running state count of how many states havebeen cycled through would be an additional trigger for exiting aparticular state. Alternative fuse cycles could also be defined usingadditional states or state counts that could include for example thecutting of tissue depending on RF output levels and electrosurgicalinstrument geometry. An exemplary graphical representation of RF energyfusing tissue utilizing script states is shown in FIG. 18 .

In accordance with various embodiments, the RF Amplifier is configuredto convert a 100VDC signal from a power supply to a high powersinusoidal waveform with a frequency of 350 kHz, which will be deliveredto the ABDI and eventually the connected electrosurgical tool. Theamplitude of this signal in one embodiment is determined by a duty cycleof a plurality of input signals from the controller.

The RF Amplifier in one embodiment is configured with circuitry toensure that there is dead time between PWM signals to prevent the PWMsignals from the controller to be both ON at the same time. A 1:2transformer of the RF Amplifier provides isolation between the PWMsignals driving an H-bridge and a two stage low-pass filter. The outputof the filter is a continuous 350 Khz sinusoidal waveform. The RFAmplifier includes a plurality of relays that are set by the controllerto direct the 350 Khz signals from the output of the filter circuit tothe device ports of the ABDI.

The RF Amplifier in accordance with various embodiments includes aplurality of shunt resistors, e.g., two shunt resistors for each of thedevice port. Voltage and current are measured across the resistors andin one embodiment are provided to two independent RF Sense. Relays onthe RF Amplifier are set by the controller FPGA to direct a tissuemeasure signal from the controller to the device ports. In addition, atransformer is provided to isolate the tissue measure signal from thedevice ports. Power supply control signals pass through the RF Amplifierto the controller and in one embodiment the RF Amplifier includes anover-current detection circuit to determine if current supplied exceedsa specific threshold and/or a voltage monitoring circuit to determine ifvoltage supplied exceeds a specific threshold. PWM signals, RF energyshutdown signals, RF Sense control signals and relay control signals aresupplied from the controller to the RF Amplifier. RF Sense analogsignals, various RF sense fault signals, power supply control signals,passive measurement signals and standby power signals are supplied fromthe RF Amplifier to the controller.

In one embodiment, the RF Amplifier includes gate drive circuitry thattakes at least two, 180° out of phase, 350 kHz PWM signals from thecontroller, to create non overlapping PWM signals that are fed into gatedrivers in a power stage to generate the output RF signal or energy.Non-overlapping signals prevent damage to components in the power stage.Before the signals enter the power stage they are isolated to separate anoisy power ground from a quiet signal ground. The PWM signals at thepower stage are fed into the gate drivers which take lower power PWMsignals and produce high current drive input signals to the MOSFETs.

The controller provides two PWM signals with a certain pulse widthdepending on the desired RF output. The H-Bridge topology utilizes atleast four gate drive signals to drive MOSFETs in the circuit. Thesefour signals are attained by generating inverted counterparts for thetwo PWM signals. In addition, the RF Amplifier prevent a pair of signals(i.e. a first PWM signal and an inverted/second PWM signal) to be HIGHat the same time. Having both signals HIGH at the same time maypotentially cause a shoot-through condition which can potentially damagecomponents of the generator.

Two RC circuits in one embodiment of the RF Amplifier ensure that thereis a dead time where both signals are off. Similarly, the other pair ofsignals also has two RC circuits to ensure dead time. The RC circuitshave a shorter time constants to account for propagation delays.

In one embodiment, signals that can stop the propagation of PWMA andPWMB (i.e. a first PWM signal and an inverted PWM signal) to the gatedrivers independently are provided. For example, one such signal isgenerated by the controller FPGA and the other signal is generated bythe microcontroller. The PWM signals continue to propagate throughisolators which separate the noisy ground from the quiet ground, whereall the high power switching circuit is referenced to. These signalscontrol the gate drivers, which converts the lower power PWM signals andproduce a signal with high enough current to force the MOSFETs intosaturation. Resistor and diode circuits at the output of the gatedrivers are tuned to achieve the desired rise and fall times.

PWM DAC SPI lines allow the controller FPGA to communicate with the PWMDAC. The PWM DAC uses a DAC with the SPI interface to create a 4.452Volt output. This output passes through an op-amp buffer and then isswitched at 700 kHz, 50% duty cycle to create a 700 kHz square wave. Assuch, the PWM DAC sets a DC level initially, e.g., at power up, that isswitched at 700 kHz to create a square wave output. This signal is thenfed to an integrator stage which results in a 700 kHz triangle wave atthe output. In particular, the integrator circuit causes a slopeproportional to the input voltage. The amplifier is the other half. Thischanges the square wave into a triangle wave. The output is a 700 kHzwave with a duty cycle proportional to the error output. This signalgoes to the FPGA Combined PWM input and the FPGA alternates these pulsesto create first and second PWM outputs that operate the FETs on theinput side of the RF transformer.

In particular, by combining the resulting triangle wave with the errorsignals from an RF control loop, the resulting signal represents a pulsewidth modulated signal that is used to drive the RF amplifier. Since theRF amplifier includes a full H-bridge output stage, two drive signals,each 180 degrees out of phase with the other are used. The PWM SignalController in the controller FPGA takes in the combined PWM signal andsplits it into two signals. During the first half of the 350 KHz outputcycle the FPGA routes the combined PWM signal to the first PWM output,and the second PWM output is held at 0 V. During the second half theFPGA routes the combined PWM signal to the second PWM output, and thefirst PWM output is held at 0V.

In one embodiment, the first and second PWM outputs which drive the RFamplifier are only enabled if the microcontroller has requested the RFenergy to be ON, e.g., enabled the RF amplifier output. If fault isdetected while RF energy is active or being supplied, the PWM signalscan be immediately disabled and the microcontroller alerted.

The microcontroller is able to control the RF amplifier output level bysending the desired voltage, current and power levels to the controllerFPGA. These levels or set points are used by an analog RF control loopcircuit which regulates the output power of the amplifier to meet theset points.

The Power Stage Circuit is configured to take the PWM signals producedin the gate drive circuit and generate a continuous sinusoidal signal,which is passed off to a relay circuit. The PWM signals drive MOSFETs inthe H-Bridge configuration. The output of the H-Bridge is connected to a1:2 transformer via a decoupling capacitor and a fuse. The transformerisolates the +100V power supply from the energy output to the patient.The circuit operates such that a first state follows second statecontinuously to produce a rectangular pulse train with a 0V offset. Whenthe first state occurs, current passes through the transformer and exitsthe transformer. This produces the positive portion of the resultingwaveform. When the second state occurs, current moves through thetransformer in the opposite direction. This produces the negativeportion of the resulting waveform. When PWMA and PWMB are either HIGH orLOW at the same time, the resulting waveform goes to 0 V. After thetransformer, this signal is passed off to a two-stage LC filter toproduce a continuous sinusoidal waveform.

The two-stage LC filter is a low pass filter designed to provide a 0 dBgain at 350 kHz. The load resistance is the resistance across the tissuebeing sealed. A series capacitor in one embodiment is placed in order tominimize the possibility of neuromuscular stimulation.

In various embodiments, the controller includes a microcontroller thatis generally responsible for overseeing the RF energy configuration andactivation and the user interface. The controller also includes a FieldProgrammable Gate Array (FPGA) that is generally responsible forsupporting the microcontroller by proving access to analog data andsupervising the control circuits. The controller in one embodiment alsoincludes a plurality of complex programmable logic devices (CPLDs) forhealth monitoring.

The microcontroller in one embodiment has an interface to the FPI toprovide a user interface and indicate fault conditions/alarms, aninterrupt input that indicates that a fault condition has been detectedand an interrupt input that indicates that a front panel switch haschanged states. The controller FPGA has parallel access to analog andcontrol data, access to the front panel switches and an output thatindicates a change in their state, and access to Device 1 and 2 inputsand outputs. In one embodiment, the controller FPGA has an active serialconfiguration interface for programming the FPGA and, in one embodiment,is the master for a system SPI communication bus for read and writeaccess to the controller CPLDs and the RF Sense FPGAs.

The controller FPGA provides an interface to the ADC circuit thatmeasures feedback voltage, current, power and phase, reads voltage andcurrent set points and errors. The voltage, current, power and phasefeedback voltages are measured redundantly by two groups of ADCs poweredby different voltage references. The controller FPGA controls a DACcircuit that generates analog set points for voltage, current, andpower.

The controller FPGA provides a clock, SPI DAC interface, and 700 kHzswitch signal for the triangle wave generator and an input for the 700kHz PWM circuit that generates 350 KHz +/- 350 Hz outputs to a drivercircuit of the RF Amplifier. The controller FPGA also detects when adevice is connected. In various embodiments, the controller FPGA detectsand provides outputs that indicate which device is active and PWM syncsignals that are 90° out of phase (sine and cosine) to the RF Sense. Thecontroller FPGA in various embodiments has an output to themicrocontroller that indicates that a fault condition has occurred andhas outputs to control the output/tissue measure relays.

The controller in one embodiment includes an analog control circuit toprovide closed-loop control of the RF energy output using DAC outputs asset points and top voltage, current, and power RF Sense outputs asfeedbacks. The output will be a combined PWM input to the FPGA.

The controller in one embodiment has redundant Complex ProgrammableLogic Device (CPLD) circuits generally responsible for detecting errorconditions and shutting off the output when they occur. Each CPLDcircuit is configured to have an output that operates an independentcircuit that disables the RF output (Gate Power Control circuitry).Additionally, each CPLD circuit is configured to have a digitalrepresentation (ADC) of the RF sense 1 and RF sense 2 voltage, current,power, and phase outputs from the RF Sense. If any of these signalsexceed minimum or maximum limits the CPLD circuit will disable the RFoutput.

In one embodiment, the controller CPLDs control load switches that allowthe controller to independently turn off supply voltage to gate driversand eventually the supply of RF energy.

The controller includes a plurality of CPLDs for detecting faults/errorconditions. The CPLDs monitor the same signals for redundancy. Theanalog inputs that come from RF sense, after passing through the filterstage, get multiplexed and the outputs are fed to ADCs. From there, theoutputs pass to a digital isolator which is used a voltage levelshifter. Output of digital isolators feeds directly into the CPLD’sbidirectional I/O.

The CPLD detect differences between RF sense 1 and RF sense 2 analogvoltages or values (voltage, current, power, and phase) obtained from aplurality of RF Sense circuitry, e.g., RF sense 1 and 2. When themagnitude of the difference between RF sense 1 and RF sense 2 is greaterthan a maximum error value, the CPLD generates a local fault. Examplesof other faults are when either voltage or current feedback signals forthe RF sense 1 or 2 exceed predetermined limits, when the phaserelationship between the synchronization signals is not valid for the RFsense 1 or 2.

The controller in one embodiment includes a passive measure circuit thatis configured to compute absolute impedance and phase of tissue incontact with the connected electrosurgical tool. The passive measurementcircuit in one embodiment includes a calibration resistor circuit and istransformer isolated from the patient.

The controller includes passive measure circuitry that includes aplurality of subcircuits; an impedance analyzer, a voltage reference, alow pass filter, and a measurement amplifier. This circuit iselectrically isolated from the patient by a transformer and can beconnected to a known value resistor for calibration.

The impedance converter and network analyzer has an AC output that setto 100 kHz and this output passes through a filter circuit that removesharmonics from the 100 kHz signal and provides a current source that candrive low impedance loads. The passive measure amplifier uses theimpedance of the tissue as the feedback so that the output isproportional to the impedance of the tissue.

Referring to FIG. 9 , the generator 10 receives script information fromthe electrosurgical device or instrument 20 when the device isconnected. The generator uses this script information to define a numberof states and the order of execution of the states.

The script source file or script information written by the devicescript author 100 and not resident on the instrument or the generator 10is text or user readable. The script information is compiled using ascript complier 105 to generate a device script database or binary file(SDB) 101. The script binary file is transferred by a device keyprogrammer 107 to a memory module that is connectable or incorporatedinto the electrosurgical instrument 20 via a device key 102. As theelectrosurgical instrument is connected to the electrosurgicalgenerator, the generator authenticates the script binary file and/or theinstrument (108). The generator validates the script binary file (109)and if validated the operations engine utilizes the script initiated bythe actuation by the connected instrument (110). Script source file inone embodiment is a text file containing a device script that isspecific for a specific electrosurgical instrument, generator and/orsurgical procedure. The script source file for a device in oneembodiment includes information containing parameters and a script(states, functions, events) for the electrosurgical generator and/orelectrosurgical instrument. After successful validation, the scriptcompiler assembles data into a binary format that defines a statemachine for use by the electrosurgical generator. Script compiler asshown in FIG. 9 in one embodiment is separate from the electrosurgicalgenerator and is responsible for reading in text from the script sourcefile and validating its contents.

When the memory module is inserted into the generator, the generatordownloads a binary file that is stored in a ferromagnetic random accessmemory (FRAM) or microcontroller disposed within the module. The binaryincludes logic for implementing the above-described treatment algorithm.The generator includes firmware/software responsible for processing thebinary to authentic the connected instrument and to execute the binaryfor performing the treatment algorithm. In this manner, the generator isconfigured to operate only with authenticated, compatible hand tools.

In one embodiment, instrument scripts or script database represent aninstrument process for a specific or given instrument. The instrumentscripts are stored on memory connected to or integrated with aninstrument, the controller or a combination thereof. The event handlerresponds to specific events, such as a switch activation/de-activation,instrument positions or exceeding measurement thresholds. The operationsengine based on the detected event if appropriate for a given eventprovides output to the connected instrument. In one embodiment, an eventis a discrete change, as in a switch is asserted or de-asserted.

Script state is a block or set of script functions or operationconditions and script events or indicators. Script functions areconfigurable instructions for controlling the generator and/or theinstruments. Script operators are logical and comparison operationsperformed during a script event evaluation. Script parameters areconfiguration data used by all states and events of a script and in oneembodiment are declared in their own dedicated section of the scriptfile. Script events are a discrete change in an electrosurgicalgenerator measurement. When a Script Event occurs, for example, asequence of script functions is executed.

In one embodiment, the controller has a specific or predetermined fixedinstrument script for a specific input receptacle. As such, only thisinstrument script is used for the instrument connected to the particularinput receptacle. The event handler receives and identifies instrumentevents or indicators, such as a switch activation/de-activation event ora measurement event (e.g., phase threshold exceeded). The operationsengine formulates requests or operations to the RF amplifier to controlRF output, output selection and/or selection of outputs. Other events orindicators detected include detecting hand and foot switches, jawswitches, phase over and phase under-after-over events, shorts andopens, instrument script states. Keywords in the scripts assist theoperations engine to extract operational commands and data forinstrument operation based on a detected event identified by the eventhandler.

The script in one embodiment controls the voltage and current outputsettings as well as sequences of voltage and current settings.Generally, a small blood vessel will fuse very rapidly while a largevessel may take several seconds. Applying a large amount of current to asmall vessel may cause excess tissue damage, while using a small amountof current will take an unacceptably long time to perform the fusionfunction. In one embodiment to modify instrument performance the scriptcan initially command a small amount of RF current, and if fusionendpoint is not reached in less than one second for example a highcurrent is commanded to speed the fusion of a large vessel. Anotherscript usage to modify instrument performance in one embodiment is toswitch from one operation (fuse) to another operation (cut) and forexample to reconfigure the instrument electrodes and ESG output whichsimplifies a multistep process such as fuse and cut. When the clinicianstarts the process the script will first setup the unit for the fusion,measure the tissue phase angle that indicates the fusion endpoint. RFpower is delivered until the fusion endpoint is reached. The unit willthen turn off RF power and indicate that fusion is complete. The unitthen switches the electrodes to a cut configuration, sets the RF outputfor cut, and restarts the RF output. The cut operation is stopped by theclinician when the cut is completed.

In one embodiment, upon activation of a switch coupled to theinstrument, the controller detects the switch closure, and authenticatesthe instrument or device, checks the instrument’s expiration status,and/or initializes internal data structures representing thereceptacle’s instrument. A subsequent activation of the instrumentswitch initiates an event that causes the script to direct the generatorto supply RF energy. The controller logs the usage to both theinstrument and the generator. When the instrument is disconnected fromthe receptacle of the generator, the controller resets the informationassociated with the receptacle. The controller in one embodimentconstantly monitors the generator for proper operation. Unrecoverableerrors and faults are announced and further operation of the system isprevented. All faults are stored in the controller’s memory and/or theinstrument’s memory.

Data from a specific procedure (e.g., from power-up to power-down) isstored on each instrument. The instrument additionally holds the datafrom a procedure, i.e., the number of instrument uses, the power settingand faults. Each instrument in one embodiment holds the information fromall other instruments as well. Instrument memory includes some or all ofthe following parameters, but is not limited to these parameters: serialnumber of generator, time stamp, tissue assessment and endpoint settingfor each instrument use, cut, fuse, power setting, duration of RF andendpoint (auto stop, fault, manual stop, etc.).

In accordance with various embodiments, the Script Engine controls RFactivation through a Script Database driven state machine. The ScriptDatabase can be read into the Script Engine via the tool ports when adevice is plugged in or via a diagnostic port. The Script Engine waitsfor an event to be recognized by a Script Event Handler, and thenexecutes functions associated with the received and recognized event. Inone embodiment, initially, after executing a sequence of functions thatconstitute a state’s setup or a state’s event actions, the Script Engineinstructs the Event Handler to check for events and then waits fornotification from the Event Handler that an event has occurred. As such,the Event Handler checks for any event or combination of events whichwould cause the script engine to transition from a present state to anew state.

The Script Engine in accordance with various embodiments performsrun-time checks to ensure that the executing script cannot damage thegenerator. In one embodiment, a Script Database is a binary data blockcontaining a tokenized encoding of a script file. A Script Database isloaded by an external task into one of two sections of FRAM or SRAMmemory (a region for each of tool ports). Script Binary Database is abinary file generated from a Script File by the Script Compiler andexecuted by the Operations Engine to control the operation of theelectrosurgical generator and/or the electrosurgical instrument.

As previously described and described throughout the application, theelectrosurgical generator ultimately supplies RF energy to a connectedelectrosurgical instrument. The electrosurgical generator ensures thatthe supplied RF energy does not exceed specified parameters and detectsfaults or error conditions. In various embodiments, however, anelectrosurgical instrument provides the commands or logic used toappropriately apply RF energy for a surgical procedure. Anelectrosurgical instrument includes memory having commands andparameters that dictate the operation of the instrument in conjunctionwith the electrosurgical generator. For example, in a simple case, thegenerator can supply the RF energy but the connected instrument decideshow much energy is applied. The generator however does not allow thesupply of RF energy to exceed a set threshold even if directed to by theconnected instrument thereby providing a check or assurance against afaulty instrument command.

As described generally above and described in further detail below,various handheld electrosurgical instruments or instruments can be usedin the electrosurgical systems described herein. For example,electrosurgical graspers, scissors, tweezers, probes, needles, and otherinstruments incorporating one, some, or all of the aspects discussedherein can provide various advantages in an electrosurgical system.Various electrosurgical instrument embodiments are discussed below. Itis contemplated that one, some, or all of the features discussedgenerally below can be included in any of the embodiment of instrumentdiscussed below. For example, it can be desirable that each of theinstruments described below include a memory for interaction with thegenerator as previously described. However, in other embodiments, theinstruments described below can be configured to interact with astandard bipolar power source without interaction of an instrumentmemory. Furthermore, although it is contemplated that certain aspects ofthese embodiments can be combined with certain aspects of otherelectrosurgical instruments within the scope of this application.

As discussed above with respect to FIG. 1 , an electrosurgicalinstrument can include a memory. The memory can include a configurationdevice module. The configuration device module can store certain typesof instrument data. For example the configuration device module canstore operational parameters for the instrument, including software tobe transferred to an electrosurgical unit upon successful electricalconnection to the electrosurgical unit. These operational parameters caninclude data regarding various electrosurgical procedures to beperformed by the instrument and corresponding energy level ranges anddurations for these operations, data regarding electrode configurationof an instrument, and data regarding switching between electrodes toperform different electrosurgical procedures with the instrument.Advantageously, changes to instrument profiles and periodic instrumentupdates can be rapidly made without downtime to electrosurgicalgenerators, as the data for instrument operation can reside inelectrosurgical instrument itself, rather than the generator.Accordingly, updates can be made during instrument production.

The configuration device module can further store a data log comprising,for example, a record of information of each previous instrument use.For example, in some embodiments, the data log can contain timestampdata including an electrosurgical unit identifier, a log ofelectrosurgical procedures perform by the instrument, and a log ofdurations and energies applied to the instrument. In some embodiments,it can be desirable that use of a particular instrument is limited to amaximum usage period or number of procedures, especially whereelectrosurgical instrument has not been configured for sterilization andreuse. Accordingly, in some embodiments, the configuration device modulecan be configured to prevent operation of an instrument after apredetermined usage or number of procedures. In some embodiments, aninstrument can comprise a mechanical lockout in addition to or in placeof the data log, such as a breakaway single-use connector to reduce thepossibility of unintended reuse.

The electrosurgical instrument in one embodiment has two separateelectrodes capable of carrying RF energy (375 VA, 150 V, 5 A at 350 kHz+/- 5 kHz). The maximum output RF voltage is 150 Vrms, +/- 7.5 Vrms. Themaximum output RF current is 5 Arms, +/- 0.25 Arms. The maximum outputRF power is 375 VA, +/- 18.75 VA.

In accordance with various embodiments, an electrosurgical instrument 20is provided. The instrument 20 includes an actuator coupled to arotatable shaft relative to the actuator. The elongate shaft has aproximal end and a distal end defining a central longitudinal axistherebetween. At the distal end of the shaft are jaws and at theproximal end is the actuator. In one embodiment, the actuator is apistol-grip like handle. The shaft and jaws, in one embodiment, aresized and shaped to fit through a 5 mm diameter trocar cannula or accessport.

The actuator includes a movable handle and a stationary handle orhousing with the movable handle coupled and movable relative to thestationary housing. In accordance with various embodiments, the movablehandle is slidably and pivotally coupled to the stationary housing. Inoperation, the movable handle is manipulated by a user, e.g., a surgeonto actuate the jaws, for example, selectively opening and closing thejaws. In various embodiments, the instruments comprise an advanceablecutting blade that can be coupled to a blade actuator such as a bladetrigger of the actuator. A blade actuation mechanism can operativelycouple the blade trigger to the cutting blade.

Attached to the distal end of the elongate shaft are jaws that comprisea first jaw and a second jaw. In one embodiment, a jaw pivot pinpivotally couples the first and second jaws and allows the first jaw tobe movable and pivot relative to the second jaw. In various embodiments,one jaw is fixed with respect to the elongate shaft such that theopposing jaw pivots with respect to the fixed jaw between an open and aclosed position. In other embodiments, both jaws can be pivotallycoupled to the elongate shaft such that both jaws can pivot with respectto each other.

Attached to the first jaw is a conductive pad. In one embodiment, theisolated wire is routed to electrically couple the conductive pad on thefirst jaw to the wiring harness in the actuator. The isolated wireextends from the distal end of the protective sleeve which is housed atthe proximal end of the second jaw and extends into the first jaw. Thefirst jaw can have a slot positioned to receive the isolated wire. Theisolated wire then extends through a hole in the first jaw and dropsinto a slot in a nonconductive portion. The isolated wire then extendsto the distal end of the nonconductive portion and drops through to theconductive pad.

Turning now to some of the operational aspects of the electrosurgicalinstruments described herein, once a vessel or tissue bundle has beenidentified for sealing, the first and second jaws are placed around thetissue. The movable handle is squeezed moving the movable handleproximally with respect to the stationary housing. As the movable handlemoves proximally it pushes a pull block. The pull block engages with apull tube causing the pull tube to move proximally. Proximal movement ofthe pull tube pivots the first jaw towards the second jaw effectivelyclamping the tissue. The force applied to the tissue by the first jaw istranslated through the pull tube and pull block to the movable handle.Once the preloaded force has been overcome, the movable handle willbegin to move a sliding pin distally. When the preload on the spring hasbeen overcome, the movable handle pivot point shifts from the slidingpin to the rear portion of the pull block where it contacts the movablehandle. The sliding pin can advance distally because the preloaded forceon the trigger spring has been overcome.

The continued manipulation of the movable handle pivots the movablehandle to a location where the movable handle engages with a latchmechanism that maintains the movable handle in the engaged position andprevents the handle from returning to an opened position. From theengaged position, sealing radio frequency energy is applied to thetissue by depressing the power activation button. Once the tissue hasbeen fused, the movable handle can be reopened by continuing proximaladvancement to a position that allows the latch mechanism to disengage.

The force regulation mechanism reduces the risk that an extremely largeamount of force is applied to the tissue. If too much force is appliedto a vessel or tissue bundle, potential damage could occur. Thus, if avery small vessel or thin tissue bundle is clamped within the jaw, theinstrument applies the minimum amount of force required to obtain a goodtissue fuse. The same is true with a very large vessel or tissue bundle.

Once the tissue has been fused, the user can actuate the blade trigger.When the blade trigger is moved proximally, the blade lever pivots,forcing a push bar and a cutting blade to move distally. The cuttingblade advances forward and divides the fused portion of the tissue. Whenthe user releases the blade trigger, the blade spring resets the cuttingblade to its original position. When the blade trigger has been returnedto its original or initial position the user can continue to squeeze themovable handle to open the upper jaw. Continued proximal movement of themovable handle will disengage the latch mechanism to a position wherethe movable handle can be released.

The dimensions of the sealing surface are such that it is appropriatelyproportioned with regards to the optimal pressure applied to the tissuebetween the jaws for the potential force the device mechanism cancreate. Its surface area is also electrically significant with regardsto the surface area contacting the tissue. This proportion of thesurface area and the thickness of the tissue have been optimized withrespect to its relationship to the electrical relative properties of thetissue. The jaws are arranged to maintain electrically significantspacing between the jaws in relation to the thickness of tissue heldbetween the jaws.

As discussed above with respect to the electrosurgical system, in someembodiments, the electrosurgical fusion instrument can be used in asystem which monitors various operational parameters and determines aradiofrequency endpoint based on phase angle.

With reference to FIGS. 21-40 , in accordance with various embodiments,an electrosurgical fusion instrument or device is provided that inaccordance with various embodiments is removably connectable to anelectrosurgical generator. In the illustrated embodiment, the instrumentincludes an actuator 224 coupled to a rotatable shaft 226 relative tothe actuator. The elongate shaft 226 has a proximal end and a distal enddefining a central longitudinal axis therebetween. At the distal end ofthe shaft 226 are jaws 222 and at the proximal end is the actuator. Inone embodiment, the actuator is a pistol-grip like handle. The shaft 226and jaws 222, in one embodiment, are sized and shaped to fit through a 5mm diameter trocar cannula or access port.

The actuator 224 includes a movable handle 223 and a stationary handleor housing 28 with the movable handle 223 coupled and movable relativeto the stationary housing. In accordance with various embodiments, themovable handle 223 is slidably and pivotally coupled to the stationaryhousing. In operation, the movable handle 223 is manipulated by a user,e.g., a surgeon to actuate the jaws, for example, selectively openingand closing the jaws.

In accordance with various embodiments, the actuator 224 includes aforce regulation mechanism that is configured such that in a closedconfiguration, the jaws 222 delivers a gripping force between apredetermined minimum force and a predetermined maximum force.

As part of the force regulation mechanism, the movable handle 223 iscoupled to the stationary handle at two sliding pivot locations to formthe force regulation mechanism. The movable handle has a first endincluding a gripping surface formed thereon and a second end 258opposite the first end. The movable handle is coupled to a pin 256adjacent the second end. In some embodiments, the movable handle can beintegrally formed with a protrusion extending therefrom defining a pinsurface. In other embodiments, a pin can be press-fit into an aperturein the movable handle. The pin can be contained within slots in thestationary housing, such as a corresponding slot formed in a rightand/or left handle frames of the stationary housing. In someembodiments, the slots can be configured to define a desired actuationhandle path, such as a curved or angled path, as the actuation handle ismoved from the first position corresponding to open jaws to a secondposition corresponding to closed jaws.

The force regulation mechanism includes a biasing member such as atension spring 257 that biases the pin in a proximal direction. Inoperation, as a predetermined force is exerted on by movement of themovable handle 223, a biasing force exerted by the spring is overcome,and the second end of the movable handle can translate generallydistally, guided by the pin in the slots.

In accordance with various embodiments, the movable handle is slidablyand pivotably coupled to the stationary housing 228 at a locationbetween the first and second ends of the actuation handle. An actuationmember such as a pull block 251 is coupled to the actuation handle. Whenthe movable handle is moved proximally, the pull block also movesproximally and longitudinally, closing the jaws 222 thereby clamping anytissue between the jaws. The pull block 251 in accordance with variousembodiments is rectangular having open top and bottom faces and a closedproximal end. The movable handle extends through the top and bottomfaces of the pull block. An edge of the movable handle bears on theproximal end of the pull block such that movement of the movable handlerelative to the stationary housing moves the pull block longitudinally.A distal end of the pull block in one embodiment is coupled to anactuation shaft such as a pull tube, bar, or rod, which can extendlongitudinally along the elongate shaft 226. Thus, in operation,movement of the movable handle from the first position to the secondposition translates the pull block 251 longitudinally within thestationary housing, which correspondingly translates the pull tubegenerally linearly along the longitudinal axis with respect to theelongate shaft 226. Movement of this pull tube can control relativemovement of the jaws 222.

In accordance with various embodiments, the actuator 224 includes alatch mechanism to maintain the movable handle 223 in a second positionwith respect to the stationary housing 228. In the illustratedembodiment, the movable handle comprises a latch arm 265 which engages amatching latch 267 contained within stationary handle for holding themovable handle at a second or closed position.

In various embodiments, the instrument comprises an advanceable cuttingblade 271 that can be coupled to a blade actuator such as a bladetrigger 225 of the actuator 224. A blade actuation mechanism canoperatively couple the blade trigger to the cutting blade. In oneembodiment, the blade actuation mechanism comprises a pivoting bladeadvancement link that transfers and reverses the proximal motion of theblade trigger 225 to a blade actuation shaft assembly, such as a pushbar, coupled to the cutting blade. In operation, a user can move theblade trigger 225 proximally to advance the cutting blade 271 from aretracted position to an extended position. The blade actuationmechanism can include a biasing member such as a blade return spring 263to bias the cutting blade into the retracted position.

The cutting component can be selectively moved between a proximallocation and a distal location to cut tissue compressed between the jawsof the jaw assembly. In various embodiments, the cutting blade 271 canbe a sharp blade, hook, knife, or other cutting element that is sizedand configured to cut tissue between the jaws. In some embodiments, thecutting blade includes a first sharpened edge and a second sharpenededge on each of a proximal edge and a distal edge of the cutting bladeto allow cutting of tissue when the cutting blade is moved eitherproximally or distally along a slot or channel in the jaws.

The actuator also comprises a wire harness that includes insulatedindividual electrical wires or leads contained within a single sheath.The wire harness can exit the stationary housing at a lower surfacethereof and form part of the cabled connection. The wires within theharness can provide electrical communication between the instrument andthe electrosurgical generator and/or accessories thereof.

In accordance with various embodiments, the actuator includes one ormore leads attached to rotational coupling clips configured to allowinfinite rotation of the shaft. In various embodiments, a switch isconnected to a user manipulated activation button 229 and is activatedwhen the activation button is depressed. In one aspect, once activated,the switch completes a circuit by electrically coupling at least twoleads together. As such, an electrical path is then established from anelectrosurgical generator to the actuator to supply RF energy to theleads attached to the rotational coupling clips.

In one embodiment, the actuator includes a rotation shaft assemblyincluding a rotation knob 227 which is disposed on an outer cover tubeof the elongate shaft 226. The rotation knob allows a surgeon to rotatethe shaft of the device while gripping the actuator 224.

In accordance with various embodiments, the elongate shaft 226 comprisesan actuation tube coupling the jaws 222 with the actuator and a bladeactuation shaft assembly coupling the actuator with a cutting blade 271.In various embodiments, the blade actuation shaft assembly comprises atwo-piece shaft having a proximal portion and a distal portion. Theproximal portion of the blade shaft assembly terminates at a proximalend at an interface node. The interface node comprises a generallyspherical protrusion portion which is adapted to engage the bladeadvancing lever. In other embodiments, the interface node can compriseother geometries such as cubic or rectangular prismatic protrusions. Theproximal portion of the blade shaft is operatively coupled to the distalportion of the blade shaft assembly. The distal portion of the bladeshaft can comprise a mount at its distal end for attachment of thecutting blade. In certain embodiments, both the proximal and distalportions of the blade shaft are at least partially positioned within agenerally tubular section of the actuation tube.

In various embodiments, the actuation tube is housed within an outercover tube. While the actuation tube is illustrated as a generallytubular member that can be nested within the outer cover tube, and thatcan have a blade actuation shaft nested within it, in other embodiments,a non-tubular actuation member can be used, for example, a shaft, arigid band, or a link, which, in certain embodiments can be positionedgenerally parallel to the blade actuation shaft within the outer covertube.

In accordance with various embodiments, attached to the distal end ofthe outer cover tube is a rotational shaft assembly comprising of twomating hubs and a conductive sleeve. The hubs snap together, engagingwith the outer cover tube. In other embodiments, the hubs can be of amonolithic construction and configured to interface with mating featureson the outer cover tube. The conductive sleeve can be attached to theproximal portion of the assembled hubs after they are attached to theouter cover tube. When the conductive sleeve is attached to the rear ofthe assembled hubs, the sleeve traps the exposed end of an isolatedwire. In the illustrated embodiment, the isolated wire extends from itsentrapment point under the conductive sleeve through a slot in theactuation tube and then inside a protective sleeve. The protectivesleeve and isolated wire extend distally inside the actuation tube,towards the jaws. In other embodiments, the isolated wire can be formedintegrally with a protective sheath and no separate protective sleeve ispresent in the actuation tube.

Attached to the distal end of the elongate shaft are jaws 222 thatinclude a first jaw 270 and a second jaw 280. In one embodiment, a jawpivot pin pivotally couples the first and second jaws and allows thefirst jaw to be movable and pivot relative to the second jaw. In variousembodiments, one jaw is fixed with respect to the elongate shaft suchthat the opposing jaw pivots with respect to the fixed jaw between anopen and a closed position. In other embodiments, both jaws can bepivotally coupled to the elongate shaft such that both jaws can pivotwith respect to each other.

Attached to the first jaw is a conductive pad 272. In one embodiment,the isolated wire 273 is routed to electrically couple the conductivepad on the first jaw to the wiring harness in the actuator. The isolatedwire extends from the distal end of the protective sleeve which ishoused at the proximal end of the second jaw and extends into the firstjaw. The first jaw can have a slot positioned to receive the isolatedwire. The isolated wire then extends through a hole in the first jaw anddrops into a slot in a nonconductive portion. The isolated wire thenextends to the distal end of the nonconductive portion and drops throughto the conductive pad.

In some embodiments, electrode geometry on the conductive pads of thejaw assembly ensures that the sealing area completely encloses thedistal portion of the blade cutting path. In embodiment, the conductivepad 272 and the second jaw 280 are curved at the edges to maintain adistinctive sealing surface in contact with tissue between the jaws,reduced unwanted concentrated current density and/or to assist incutting of tissue between the jaws. In some embodiments, for somesurgical procedures the outer shape of the jaws can be curved such thatthe distal ends of the jaws are offset with respect to the longitudinalaxis from the proximal ends of the jaws to improve visibility for a usersuch as a surgeon.

In accordance with various embodiments, the dimensions of the jawsurfaces are such that it is appropriately proportioned with regards tothe optimal pressure applied to the tissue between the jaws for thepotential force the force mechanism can create. Its surface area is alsoelectrically significant with regards to the surface area contacting thetissue. This proportion of the surface area and the thickness of thetissue have been optimized with respect to its relationship to theelectrical relative properties of the tissue.

The jaws are arranged to maintain electrically significant spacingbetween the jaws in relation to the thickness of tissue held between thejaws. In one embodiment, at least one jaw includes a conductive post 281extending in a direction traverse to the longitudinal direction of thejaw. The post in various embodiments protrudes through an inner surfaceof the second jaw or lower jaw assembly and towards an inner surface ora conductive pad of the first jaw.

The conductive posts in one embodiment are made from a conductivematerial such as stainless steel. The conductive post in one embodimentbeing made from a stainless steel provides high compressive and/orcolumn strength. As such, the conductive post can endure moreoperational wear and tear and can be dimensionally small relative to thedimensions of the jaw with a reduced concern of breakage or dislodgementor occupying excessive space on the jaw. In one embodiment theconductive posts are made of a material that is the same material as theconductive pad on the first and/or second jaws.

In accordance with various embodiments, multiple posts provided andsupport an inner edge of the conductive surface of the jaw that isadjacent to a blade channel within the jaw. In accordance with variousembodiments, the posts also provide additional surface texture to aidwith capturing and griping the tissue that is captured within the jawsof the device. The conductive posts however do not have and edge or anotherwise atraumatic surface to pierce, puncture or otherwise protrudethrough tissue grasped between the jaws.

The conductive post in one embodiment supports an inner edge of aconductive surface that is adjacent to the blade channel. The posts arebiased to be at the edge of the blade channel. When the jaws are closedand RF energy is supplied, the conductive post is the same electricalpotential as the conductive surface. The configuration of the conductivepost relative to the conductive surface and the conductive post beingthe same electrical potential as the upper conductive surface provide inone embodiment a tissue treating surface that is uninterrupted along thejaw. In one embodiment, the configuration and electrical potentialprovide the application of RF energy allows heating and sealing aroundthe conductive post further enhancing the seal quality or tissuetreatment of the tissue between the jaws.

Additionally, to improve seal quality and reduce the potential forhigher current density at the edges of the upper and lower conductivesurfaces, the upper and lower conductive surfaces in one embodiment havea lead-in angle 274 and/or radius 275, 283 configuration. In addition toaddressing current density the radius also presents an atraumatic radiiedge to the vessel adjacent to the area affected by RF energyapplication to help prevent cutting at the edge of the surface of thejaws.

The conductive posts in one embodiment are disposed along the jaw andeach at a differing height relative to the others such that they are noton the same plane. In one embodiment, the conductive posts as suchprovide that the first or distal most conductive post to contact tissuefirst then one or more intermediate conductive posts and finally aproximal most conductive post. In one embodiment, the distal most postis 0.005”, the intermediate is 0.004” and the proximal most post is0.003”. Such a staggered arrangement ensures the jaws or inner surfacesremain relatively parallel relative to the tissue and each other bycompensating for the deflection of the first and/or second jaws when theforce is applied. The height difference of the posts relative to the jawin one embodiment can lift or raise portions of the tissue near oradjacent the blade channel and thereby aids with the gripping of thetissue as it is being cut and thereby provides a smoother cut and easesthe cutting operation.

In one embodiment, the first jaw or upper jaw assembly comprises astamped sheet metal conductive pad 272 that is held at a distance fromthe machined upper metal jaw 275 by a high service non-conductivetemperature plastic material 276. The stamped sheet metal,non-conductive plastic material and machined upper metal jaw are placedinto a mold which is subsequently filled with a thermoplastic. Theresult of the process is an over molded upper machined or MIM (metalinjection molded) jaw, stamped conductive pad and high temperatureplastic that are fixed or held together by the thermoplasticover-molding to make the first or upper jaw. In one embodiment, theupper jaw includes an injection molded component in place of the highservice temperature non-conductive plastic material.

In one embodiment, the second jaw or lower jaw assembly comprises amachined or MIM jaw and machined or MIM electrically conductive posts281. In one embodiment, the posts and jaw are made of the same material.The jaw and posts are placed into a mold which is subsequently filledwith a thermoplastic. The result of the process is an over-molded lowerjaw and conductive posts that are fixed or held together by thethermoplastic over-molding to make the lower jaw. By the posts extendingfrom the lower jaw assembly and through an inner surface of the jaw, thestrength and/or stability of the conductive posts are enhanced relativeto the jaws and/or tissue. As such, in one embodiment, the post has aheight that is at least twice the thickness of the conductive pad. Inone embodiment, the post has a bottom portion that extends into abouthalf the thickness or depth of the first and/or second jaw. Uponassembly a jaw gap is set in a fixture and laser welded and in oneembodiment this is facilitated by a slotted hole in the lower jaw and adowel.

Referring to FIGS. 38-40 , in one embodiment, a return path connection285 is provided to connect the conductive posts to the generator. Insuch an embodiment, the conductive posts can provide additional feedbackinformation such as applied voltage, current, power and phase, or tissueproperties. In one embodiment, the return path connection provides anindicator or cutoff switch such that if the cutting blade enters the jawa circuit is developed or a deliberate short is triggered to terminateRF energy and thereby ensure that RF energy is not being supplied whilethe blade is being actuated. In one embodiment, a thermistor or atemperature sensor 286 is disposed under or inline with the conductivepost and connected back with a wire or return connection through thelower jaw to monitor the temperature, e.g., via the change in thethermistor caused by the temperature change. In one embodiment theelectrosurgical generator can then account for the temperature of thetissue and the jaws that can effect fusing of the tissue and/or theapplication of the RF energy. In one embodiment, the second or lower jawincludes plates or a capacitive arrangement or sensor 287 and in oneembodiment the electrosurgical generator can then measures thecapacitance between a bottom surface of the conductive post and aportion of the jaw to account for instrument or tissue capacitance thatcan effect fusing of the tissue and/or the application of RF energy.

In accordance with various embodiments, an electrosurgical system caninclude an electrosurgical generator and an electrosurgical instrument.The electrosurgical instrument is used in laparoscopic procedures wherethe ligation and division of vessels and tissue bundles are desired. Theelectrosurgical instrument fuses vessels by delivering radio frequency(RF) energy to tissue captured between the jaws of the device anddivides sealed tissue with a user-actuated blade. The generator canprovide an electrosurgery endpoint by determining the phase end point ofa tissue to be treated. The electrosurgical system can include more thanone electrosurgical instrument for different electrosurgical operationsand can include a variety of user interface features and audio/visualperformance indicators. The electrosurgical system can also powerconventional bipolar electrosurgical instruments and direct currentsurgical appliances.

Turning now to some of the operational aspects of the electrosurgicalinstrument or instrument described herein in accordance with variousembodiments, once a vessel or tissue bundle has been identified forfusing, the first and second jaws are placed around the tissue. Themovable handle 223 is squeezed moving the movable handle proximally withrespect to the stationary housing 228. As the movable handle movesproximally it pushes the pull block. The pull block engages with thepull tube causing the pull tube to move proximally. Proximal movement ofthe pull tube pivots the first jaw towards the second jaw effectivelyclamping the tissue. In FIGS. 27-28 , the actuator 224 is shown in afirst or initial position in which the jaws 222 are in an open positionand in one embodiment the first and second jaws opening defines about a30 degree angle.

The continued manipulation of the movable handle pivots the movablehandle to a location where the movable handle engages with the latchmechanism that maintains the movable handle in the engaged position andprevents the handle from returning to an opened position. From theengaged position, radio frequency energy is applied to the tissue bydepressing the activation button. Once the tissue has been fused, themovable handle is reopened by continuing proximal advancement to aposition that allows the latch mechanism to disengage. In FIGS. 30-31 ,the actuator 224 is shown in an engaged position in which the jaws 222are closed and the movable handle is latched.

Alternatively or additionally, the user can actuate the blade trigger225. When the blade trigger is moved proximally, the blade lever pivots,forcing the push bar and the cutting blade to move distally. The cuttingblade advances forward and divides the sealed portion of the tissue.When the user releases the blade trigger, the blade spring resets thecutting blade to its original position. When the blade trigger has beenreturned to its original or initial position the user can continue tosqueeze the movable handle to open the upper jaw. In FIGS. 32-33 , theactuator 224 is shown in a cutting position in which the jaws 222 are ina closed position and the blade trigger has been depressed advancing thecutting blade to its distal most position. Continued proximal movementof the movable handle will disengage the latch mechanism to a positionwhere the movable handle can be released. In FIG. 29 , an intermediateposition is shown in which the jaws are in a closed position and themovable handle is not latched. In one embodiment, the blade trigger maybe activated to cut tissue between the jaws and/or the fuse button orswitch may be activated to fuse tissue between the jaws.

Further examples of the electrosurgical unit, instruments andconnections there between and operations and/or functionalities thereofare described in U.S. Pat. Application Nos. 12/416,668, filed Apr. 1,2009, entitled “Electrosurgical System”; 12/416,751, filed Apr. 1, 2009,entitled “Electrosurgical System”; 12/416,695, filed Apr. 1, 2009,entitled “Electrosurgical System”; 12/416,765, filed Apr. 1, 2009,entitled “Electrosurgical System”; and 12/416,128, filed Mar. 31, 2009,entitled “Electrosurgical System”; the entire disclosures of which arehereby incorporated by reference as if set in full herein.

The above description is provided to enable any person skilled in theart to make and use the surgical instruments and perform the methodsdescribed herein and sets forth the best modes contemplated by theinventors of carrying out their inventions. Various modifications,however, will remain apparent to those skilled in the art. It iscontemplated that these modifications are within the scope of thepresent disclosure. Different embodiments or aspects of such embodimentsmay be shown in various figures and described throughout thespecification. However, it should be noted that although shown ordescribed separately each embodiment and aspects thereof may be combinedwith one or more of the other embodiments and aspects thereof unlessexpressly stated otherwise. It is merely for easing readability of thespecification that each combination is not expressly set forth.

Although the present invention has been described in certain specificaspects, many additional modifications and variations would be apparentto those skilled in the art. It is therefore to be understood that thepresent invention may be practiced otherwise than specificallydescribed, including various changes in the size, shape and materials,without departing from the scope and spirit of the present invention.Thus, embodiments of the present invention should be considered in allrespects as illustrative and not restrictive.

1. An electrosurgical system comprising: an electrosurgical instrumentarranged to grasp and fuse tissue using radio frequency (RF) energy, theelectrosurgical instrument comprises: a first jaw having a firstelectrode; a second jaw coupled to the first jaw and having a secondelectrode facing the first electrode, the first and second electrodesarranged to conduct the RF energy between the first and secondelectrodes and the first and second electrodes being made of the sameconductive material; an elongate shaft having a proximal end and adistal end and a longitudinal axis extending from the proximal end tothe distal end, the first and second jaws being pivotably coupled to thedistal end of the elongate shaft; and a conductive post incorporatedinto the second jaw and extending from the second jaw towards the firstjaw, the conductive post being stationary, made of the same conductivematerial as the first and second electrodes and having an upper portionextending past an upper surface of the second electrode and a lowerportion encased in an insulated material in the second jaw, theinsulated material separating the conductive post from the secondelectrode and conductive material in the second jaw; and anelectrosurgical generator connectable to the electrosurgical instrumentand configured to supply the RF energy through the electrosurgicalinstrument to the first and second electrodes and not the conductivepost, the electrosurgical generator comprising: an RF amplifier tosupply RF energy through the electrosurgical instrument; and an RF sensecircuitry arranged to receive a supplied RF waveform from the suppliedRF energy through the electrosurgical instrument, the RF sense circuitrycomprising a synchronous detector arranged to calculate real andimaginary voltage and current components of the supplied RF waveform. 2.The system of claim 1 wherein the RF sense circuitry is arranged todetermine a phase angle of the supplied RF energy from the calculatedreal and imaginary voltage and current components and further comprisinga controller arranged to signal the RF amplifier to terminate the supplyof RF energy when the determined phase angle is less than a predefinedphase value.
 3. The system of claim 2 wherein the predefined phase valueis a negative value.
 4. The system of claim 3 wherein the controller isconfigured to compare an identified voltage to a predetermined voltagevalue to determine the predefined phase value.
 5. The system of claim 4wherein the RF Sense circuitry measures voltage and current of thesupplied RF energy from the RF amplifier and generates DC signalsrepresenting voltage, current, power, and phase of the measured voltageand current and wherein the controller further comprises a RF smootherarranged to remove noise from the generated DC signals from the RF senseand extrapolate from the generated DC signals smooth modulated DCsignals representative of the voltage, current, power, and phase of thesupplied RF energy.
 6. The system of claim 5 wherein the synchronousdetector is arranged to calculate real and imaginary voltage and currentcomponents of the supplied RF waveform using synchronization signals. 7.The system of claim 6 wherein the RF sense circuitry calculates a rootmeans square (RMS) voltage, RMS current, apparent power and phase usingthe calculated real and imaginary voltage and current components.
 8. Thesystem of claim 7 wherein the electrosurgical instrument furthercomprises a blade movable along the longitudinal axis from a proximalposition to a distal position and back to the proximal position, theblade disposed within an outer periphery of the second jaw and thesecond jaw includes a channel through which the blade traverses therethrough.
 9. The system of claim 8 wherein the blade is made of aconductive material that is the same as the conductive material of theconductive post and an entire surface of the first jaw facing the secondjaw is smooth and flat having no indentations or pockets.
 10. The systemof claim 9 wherein the electrosurgical instrument further comprises anactuator disposed on the proximal end of the elongate shaft and arrangedto be user accessible where manipulation of the actuator moves the firstand second jaws, initiates the supply of RF energy or translationalmovement of the blade.
 11. The system of claim 10 wherein theelectrosurgical generator is arranged to supply RF energy only to thefirst and second electrodes and not the conductive post and the blade.12. The system of claim 11 wherein the electrosurgical instrumentfurther comprises a switch that causes the generator to supply RFenergy.
 13. The system of claim 12 wherein the controller of thegenerator logs the usage of both the instrument and the generator. 14.The system of claim 13 wherein the conductive post is affixed to thesecond jaw by an over-molding.
 15. The system of claim 13 wherein theconductive post is arranged to contact the first electrode.
 16. Thesystem of claim 15 wherein the conductive post has a flat upperatraumatic surface.
 17. The system of claim 16 wherein the conductivepost is disposed adjacent to the channel of the second jaw.
 18. Thesystem of claim 16 further comprising a temperature sensor disposedwithin the second jaw and proximate the conductive post.
 19. The systemof claim 16 wherein the conductive post includes a plurality ofconductive posts having varying heights and the plurality of conductiveposts includes a distal most conductive post having a height greaterthan a height of a proximal most conductive post.
 20. The system ofclaim 19 wherein the plurality of conductive posts are disposed adjacentto the channel of the second jaw.